For example I use two accounts on different servers with very different content. Personally I really like that separation.

Yeah, same here; I also have multiple Mastodon accounts. Ironically, the “everything” nature of Twitter was something that made me not use it much, because I have multiple interests some of which are quite disparate (for example, videogames, and some professional field), and so I was never really comfortable with those streams mixing readily.

With Mastodon I can easily keep them separate but also have the option to cross-post whenever I want.