Most of the players do understand it. They just feel entitled to clear content without effort and time. They don't care about their contribution, they just want the rewards and achievements - to have easier time getting carried in the next farm party.

If you join a clear party you can expect a lot of work and wipes. In farm parties the players are usually a little bit better as they at least done it before. The naysayers fear they would have to play with similarly skilled and experienced players and then they would lose easy access to content beyond their "casual" sklil, untill they improve. "Why should the experienced players play with experienced players... that is clearly not fair!" /Facepalm

This feature would cause exclusion. There is no doubt about that. But I would see it as a tiny protection of players who are getting exploited for clears atm.