The purpose is to demonize big tech. It's the new "tough on crime." Of course there's a lot to criticize, but if criticizing and making change were the real goals, the hearing would look very different. They might have done more research and make specific demands.

edit/P.S.: I don't mean to sound sorry for big tech. They're not some poor unsuspecting victims. I'm just worried that they'll try to use this hearing, especially the vague "anti-conservative bias" questions, in order to trick people into supporting EARN IT.