The problem is that without copyright all a big company has to do is steal the work of smaller unknown artists and profit from it big time. The smaller artist then has zero recourse to get any money because their avenue for profit is ruined. Copyright allows them to sue the person who stole their work and get the profits from that.
This is a complete oversimplification of everythin.
I think firstname.lastname@example.org would be much more professional.
It really depends on what part of the fediverse you are in. Mastodon is not too different from twitter that a boomer with a familiarity with twitter shouldn’t have too much trouble with a mastodon instance. The biggest thing to wrap your head around is the fact that not everything is run by a single company. So you have to find a server that you like, and then sign up on that server.
What do you define as a big corporation? And why exactly should we abolish them?