Those numbers are misleading, even if you cherrypick just the pinned threads in The Citadel, there is a 69K thread there alone, while in whole of The Citadel there is even a one 8M views thread, so this statement is factually false or an overlook.
I wouldn`t generalize these forums that way at all, as it has abundance of great threads and whole boards that have influenced the development for the better for everyone else, which can`t be said about Reddit or YouTube.
Maybe some people stick arround to watch angry whiteknights shamelessly defend every and any design decision and to laugh at it.
There are a ton of possibilities to why people stick arround here, the main being the oportunity to communicate with the developers, which you most likely won`t experience on any other platform including Reddit and YouTube, but one thing i can tell with certainty - everyone involved enough to post here on forums loves the franchise and wants to make it better, even if frustration slips away from time to time.
In any case, being an active part in the division, and back and forths between the "angry haters" and "shameless whiteknights" isn`t at all helpfull in my view.