Do RSVP raid lobbies cap at 10 trainers?

I RSVP’d to a mega Mewtwo X raid and the lobby appeared to be capped @ 10 trainers, of course there were several trainers that did not bring a mega evolved Pokémon, so there was no way to win the raid so I backed out. Are these raid lobbies capped at 10? That means everyone needs to be perfect in order to succeed, unfortunately, there’s always one or two that don’t bring a mega.