The couple of times I've seen it happen in DRS I'm 100% sure it was trolling. Party leader would attempt to queue in 3 times and it wouldn't commence at 47/48. Ready check would pass at 48/48. This would repeat until it was clear one person was purposely not pressing Commence to prevent the party from queuing into the instance. There is no way to find out who that 1 person is so it led to that DRS party to disband. I'm aware what actual AFK situations are and in that case you'd ready check and find out who that person is anyway and wait a few more minutes or kick them if they had an emergency. Someone who is deliberately trolling will remain anonymous because they won't press Commence when queuing but they'll press Yes when you ready check or say "That wasn't me" with everyone else when you try to ask in chat who is doing it.