Plex lost me when they became obsessed with trying to put advertisements in front of my grandparents when all they want to do is watch Mash on my plex server.
I've only seen ads in Plex when watching the streaming services they have integrated, which is expected. Those services need to pay for their content somehow.
Yes, but they now show their catalogue by default on every new client you log into. So you (or whoever has access to your server) have to know to hide their rows in favor of local media collections. They don't differentiate them in any way, so I hope your media libraries are named something more descriptive than "Movies & TV". Really disappointing.