Raider IO is the only real tool we have to tell if someone is gonna be a asset or a hindrance to the group before you waste a mythic key on them. It’s still not a great system as you need to have experience with high level mythics to get reliable invites but in order to get experience you need to do runs, hence the issue.
That being said, I’ve never had an issue getting a mythic+ group when I put it together myself with my own key. I guess people don’t want to put in the extra effort to get their own group and they just want a quick invite to a group while at the same time not having experience in said content.
PS. OP it takes like 5 minutes max to make an m0 group for the world quests.