Sorry but no. Then there will be a lot of complaining about how people join weekly clear groups and farm groups just for an easy clear.
I am going to blunt. Players who have cleared content have no obligations to help others clear said content.

Does the message single out players that are new or just lacking a clear? Yes, I agree. Honestly, I would probably just asking proof of clear whenever I make a pugged group for something and I am sure I wouldn't be the only one to do so.