Why are people assuming people who haven't cleared content are bads and will be incapable? Or will it just be devestating getting someone without a clear who plays better than you?

Honestly I can see where the op is coming from but I think potentially you're missing out on good players just because you're assuming someone who hasn't cleared the stuff is terrible. You've still got the potential to end up with morons who got carried.

Having said if the option was there it'd make no difference to me, their party their rulez blah blah. I would probably would not use it, unless I reaaaallly wanted to clear something in a hurry, but even then it's not going to be foolproof.