It's true, I'll boot people that don't have both stones, or Drive on Apex quests. It's not about being mean, it's just about making the quest go as well as it can for the entire group. It's akin to someone joining a GQ128+ with High Rank gear where they just want everyone else to pull the majority of the weight.
I don't boot people for armor unless it's something absurd. A set they're making with no active skills, incredibly low OHKO worthy defense, -20 or more weaknesses to something that does a bunch of that element. I don't care about Japanese DLC, or anything like that.
If you're being kicked out of rooms, just setup the event, or quest in a room you create. It's the easiest solution, even if you have to wait a bit.
One of the few times I was kicked was with my Samus gunner armor. I mean, yeah, it's over 600 defense and gemmed up to have a bunch of great abilities, but the host wasn't having any of it. I don't mind though, I'll just move to another room.