My concern isn't that it happens or should or shouldn't be punished, but that making it easier to find "easy runs" will make the button more popular than it already is to do it, making it -more- likely that a player has to do DF (if that is even an option for certain contents) or just don't do the content. I've seen this happen in MMOs even without a know your stuff button, and as I said before I can't say how widespread the button would be after implementation but that I can only assume the mindset would be more common. Problem is especially bad as content gets older. Learning parties are not as popular to join as not, since everyone wants what is easy (including the people trying to sneak in and those wanting this button to stop the sneakers, smeagol).
I see the intention here as one of less stress, a good intention if you are on the right side of the fence - but I don't think it is better for the community when the general expectation becomes "to get in, you need to have already been in". "Well find a learning party lazy scrub" - "people" are limited resources, people who would pick the harder option when they can easy mode the easy option even rarer, and so specially over time being a lazy scrub is not really reasonable anymore.
People having the right to lie, I'm not suggesting that - I think you should ask and announce yourself in, and GMs have already said that agreements at the door can be enforced (people sneaking in unannounced should be aware of that, specially if they start to kill the run).
What if we had learning dungeons about a week or two after the content is out with limited rewards:
Perhaps if every actually hard dungeon had an optional Echo Playback, where you could travel around and remember the memories of other adventurers who went through an area. Learn key parts of the dungeon solo and then after completing all memories you are counted as "completed". Could add it to the DF too.. This would increase the average know how of players in the queue, though of course some people just don't care - I've wiped to Titan HM in a party of all ilvl100+. Thinking to myself, how? lol
Having to complete a dungeon's memory sequence as each particular trinity type you want to join in, however there could be a one time seal or gil reward for each job. I say a week or two because you want the first wave to know nothing, it is a unique experience - and also over time people will be less interested in taking new people to hard contents, so this is my suggestion on allowing new people the reasonable option to earn their ticket into content queues (PF/DF).
I know it is a compromise from just never having to deal with new people but again it's not about letting people lie it's that the path to a bad community can be paved with the lazy and good intentions.
Lore wise you could have the first week or two of players completing content get placed into a pool of names the game can pull out and have you "experience", it shouldn't be a replay but you could just give a tip of the hat to the fore runners and also make legitimate explanation why a new dungeon not existing before is now "echo"-able.
@Gucci please stop assuming everyone is a lazy noob, it is insulting and inaccurate. The system will further divide because the system is defined to not allow certain groups in, by definition of the system it is just.. it makes no sense to say it wont. It has to, that is the feature of the button. By how much, that is arguable though.