Compare a chatroom or forum (incl imageboards) to reddit-like sites, and I'm sure you can already think of a few ways each pressures people to talk a different way
Even in chatrooms this occurs after your room crosses a threshold where it's large enough to start making people behave that way. They stop having conversations and start behaving more like they're in a sports stadium crowd. This is particularly annoying to deal with because overflow spaces don't work either, some people use them because they like a quieter space but the original space still typically stays above that threshold and so remains a problem.
These trends can and have been overcome
Yes and no. The different spaces produce different behaviours. But Trueanon, Hexbear and CTH all existed on spaces that overwhelmingly suffer from the problem and yet... The userbase does not. The userbase is different. If a userbase can be different despite being on spaces that would typically produce the problem, then conditions can be created in order to create that userbase. The issue is one of finding the correct method to produce those conditions, as owner of the space.