How is that any different from the way most games release now? Games are usually pretty bad on release and then get patched over the next few months, sometimes adding gamechanging features months after the game is released and the majority of sales have been made. What difference is there between a "real" release and early access besides just PR rhetoric?
I can't think of one game that was released in full release that was unfinished. I don't mean bugged or crappy, mind you, but unfinished as in there were features missing that were going to be added later according to official statements from a developer. Also game changing features are usually added for free only by small indie teams, larger game companies will release DLCs instead. What games did you have in mind when you wrote that?
To be honest though, I am not sure that there even is a point in debating what Early Access is or isn't, at the end of the day you are right when you say that it's just a label with no significant legal meaning (it's not like buying a game in general comes with a binding contract anyway, if you don't like you are not even entitled to return it, barring store policies which are entirely up the platform you bought the game from). Bannerlord was released in the state that it is in, and there is no doubt that it is in much worse shape than anyone was expecting. They are working on fixing it, and so far for what concerns single player I am seeing good signs of changes happening in the right direction.
I understand that the multiplayer beta was a disaster, but as for right now that doesn't seem to be the case for single player (judging from some of the most recent Callum's posts they are also trying to address multiplayer, but I know better than to get myself into that discussion
). I don't think TW is in it just for the money, or they would have just released the game in full release with some nominal bug fixes and called it a day.
Early Access as a concept is one of the biggest ripoffs in gaming, rivalled only by microtransactions. It's super effective though, because it gets you an instant army of defenders smugly going "it's early access!" whenever any criticism is made. All the while they all imagine that whenever the mythical "real release" happens, all the issues will have been sorted and a cornucopia of wonderful features will have been added. Usually, the reality falls far short of that.
Sometimes it doesn't though! And you know, there is a simple solution to that, just don't but any Early Access title. For example, I don't ever pre order a game because I don't believe in paying for something that hasn't come out yet.