BuddyPress.org

https://buddypress.org/developers/nuprn1 rich! etiviti wrote a suite of plugins one of which is ‘BuddyPress Restrict Group Creation’
Don’t allow your members to sign up and instantly create groups set a time period they have to wait, spammers won’t wait, genuine members will not mind if it’s clear to them they have to wait a few hours, a day or whatever.