The username is structured as username@instanceurl so they will know it’s you based on the instance url

They can change find new employees

the path to full privacy

Someone already explained to you the difference between privacy and secrecy, which is quite simple.

Privacy: you don’t want your mother to see a lewd picture from you, but you would want your partner to Secrecy: you don’t want anybody to know you eat poop

I’m also not saying ‘corporations bad’. I’m saying ‘corporations are unnecessary for the fediverse to exist and probably will do bad things’.

This means corporations bad tho. Which I agree with btw