Wait a sec, they just added this, lets give it a chance and make suggestions to improve it before removing anything.
Sometimes it shows similar threads and other times it struggles to provide useful threads.
This probably because it's all automatic, I'm sure it can be improved.
As for the automatic process, there should be a formula or algorithm to calculate the probability of the threads appearing in the suggestion, as well as their position (higher probability = higher similarity ? leads to first position in the suggestions)
The algorithm shouldn't be too hard to create and improve, it's not like YouTube or ads where it's personalized suggestions, here the main focus is to be objective, it's all the same for everyone. I will give some ideas and feedback on how to improve it:
The formula to calculate the probability should have multiple variables to improve robustness and accuracy.
AI and deep learning algorithms could be an option.
Looking for the same or synonym words, expressions in the title, post and comments (but in different variables, so that similar words in the title confer a higher portability than similar words in the comments, for example). Also watch out for spelling errors, plural/singular and abbreviations (e.g: devs and developers).
Fix the errors in tags (misspelled, singular/plural, misused, add new ones) and use them as part of the algorithm, this "key words" should be a good indicator of the content.
Number of times relevant words or "key words" appear in the text (again prioritize title and op post over comments - some titles and posts are not that indicative of the intent or content, not sure if it's a problem)
Consider the punctuation in phrases (titles, op post, comments). A thread with a "question" title might be similar to other question titles of other threads.
Threads posted under the same or similar category should compute higher probability. E.g.: In a suggestion thread, "similar threads" would favor threads in the suggestion category...
A variable that considers the quoting from other threads, op post and comments.
Consider op post length, text format, check if the thread has the same media, images, links...
Prioritize suggested posts by date, number of views, number of comments... could be a possibility by default but also in filters.
Curated threads, pinned, dev posts/replies and other important ones should be prioritized and moderated in the most "popular" threads (see if it's relevant, add relevant ones to the suggestions)
Add the option to minimize the suggestions as default and a button (I think for now it should appear for everyone, so that we can provide feedback, I'm not against it showing by default but it's a thing to consider).
Instead of putting this at the bottom you could consider putting this minimized at the top, somewhere between the title and the comment section.
Moderate the "similar threads" in the most frequent and popular posts/threads.
Allow members to add new threads to the suggestions threads (possibly, after it gets approved by a community moderator).
Allow members to change the position and effectively the probability of the suggested threads by giving us the option to move up or down threads (ranking), then based on the overall and average position change made by members, compute new probabilities, the changes appear to everyone. (a save button would be added to send the info of the position change to the database). A problem with this is that people will likely be biased towards their threads, but with the "average" of probabilities this is not significant. Automatic and manual (community moderators) mechanisms could also exist to recognize abuse, looking for biased patterns (prioritizing your own posts). User and members could also edit the positions and send for moderation approval. If for members this is not possible, then assign this option (changing positions and priority/probability of suggested threads) only to community moderators and such, so they can passively improve the system.
Add a "dismiss/delete/not related this thread suggestion" option (the intent is to compute a lower a probability or dropping in position after the next database update). Also susceptible to moderation verification.
When sending for moderation add the option or require to add text explaining the change.
Add the option of "show more" (continue pumping threads out based on probability, this goes in line with the previous points - people can select threads)
Gather data on clicks of the suggested threads and alter the probability based on clicks. (this could be another metric or an alternative to the manual selection - again, I think the individual subjectivity does not affect the integrity of the results because, in the end, the sum of the subjective choices tend to an objective result; and this is only one variable, other variables give robustness)
Consider the "time viewing the suggested thread". Higher viewing time higher chance of relevance and similarity.
Add the option "is this a similar thread?" or "is this related", in the front of the suggested thread and/or in the new opened page you just clicked on.
When you click in one of the "similar threads" open a new tab instead of loading the new page in the same tab. (it's only my personal preference it might not be better this way for some reason)
Add the option "search for similar threads". This would open up an extended version, more of the suggested threads, the user could even alter certain search parameters like key words to "refine" the search. A pop up window saying "is this similar?" could then appear when you click a thread (that opens in a new tab, like a mentioned previously). Gather the data of the clicked threads, time of viewing, feedback from the pop-up... and then improve the algorithm.
Have an option to show random pop up windows that appear always, often, rarely or never (depending on the configurable choice of the user) when you click thread. The pop-up would ask if the thread you clicked is related or is similar to the automatic suggested "similar thread(s)", then the user would select yes or no if multiple choices appear or in a scale of 0 to 5 if you are comparing only to one thread, for example. Once the user selects their yes/no or rating, then selects the option to "continue" which pops up another set of similar threads, and so on as long as you click continue, but a certain threshold should exist. We would always have the option to "close" the pop up at any time.
If possible, a real time prediction/suggestion/completion when searching for something (like google) could be added.
Add more search functionalities, something like
this.
Afaik, the goal is to objectively suggest similar threads but who knows if this could evolve to a personalized experience. A simple way of personalization would be suggesting similar threads in other languages. Consider the language the forum is in, the country the user is from, check if he commented in other languages forums, look at groups he's in...
An option to show similar threads in X language could be added.
The gathered data could be used and applied to other things. Statistics to make forums and game decisions, see the content people actually want, faster and more informed decisions by devs, better inform forum users, better moderation...