You still don't have to do much these services still exist, even for Mumble. Their limitation is scaling. So if you want way more than just a handful of people, you either start charging everyone an entrance fee, or you cap the server.
Discord's limitation is scaling as well, to be honest. It's incredibly hard to follow a server full of tens of thousands of people. Just because something can scale in a technical sense doesn't mean it will scale in a human one.
