>If we treat those platforms as private. Then we are playing in s/o's backyard. You are totally at their mercy. They have every right to kick you out if they don't like your face. It's their property. You are a guest.

Maybe this depends on the laws of a country. Also, IMHO either a company offers their services to everyone or to no one. There are, of course, exceptions that aren't really exceptions. Creative work in an "exception". For instance, French painter Monet was so popular that he could choose his customers.