I do not see a problem with the OP's suggestion. It would be a tool that will allow a player to have better control of their time as well as help others that fall on to the same experience page of the content they want to clear in an efficient manner. That party leader is putting his/her time on the table and it should be respected. The other experienced players are also putting their time on the table that requires courtesy. Anyone else that stands here trying to make what the OP has suggested out to be something monstrous/segratorial/anti-social needs to take it elsewhere. If someone needs to clear content for the first time, then by all means, grab the help of your FC/LS-mates or throw it up in the PF as a "learning" party or "need help" party. If experienced players wish to help those that have not cleared a particular content, they will open up those doors and assist. Do not sit here and try to dictate to them what they should or shouldn't do - it is not your place and you have no leg to stand on to try to enforce your misplaced moral values on this subject. They pay their subscriptions like all other players and will play the game as they see fit. If you fear elitism - as someone has already said, it is already prevalent in the game. What is to stop party leaders or entire parties voting to kick someone? I would even go as far as to say the OPs request would be excellent as it would prevent the non-clear people from being kicked when it has been discovered they lied - they just wouldn't be in the party in the first place!

Of course, just my opinion. <shrug>