People need to understand the difference between not being able to advance and not being able to advance as fast. Realistically, a casual player will never be able to not advance in anything. However, what most people that want a bigger gap between hardcore/casual is that the hardcores shouldn't be capped so the casuals can catch up faster. Kind of like how fatigue worked, a hardcore could grind all he wanted but eventually reach restrictions, but a casual could go at his pace and advance at a ratio that is higher than the hardcore's.

Personally, I think this is why I believe hard mode in dungeons are a wonderful thing. Casuals can experience the same content without having the spend as much time but the people that spend more time in the game can advance at a faster rate and go against a more difficult challenge at the same time. This is why I'm happy that Yoshida said that he will add this in 2.0.

I myself am completely against on how XI worked. Needing a countless amount of time to actually advance in the game is not good game design. However I do agree with things such as a party reaping more rewards than solo.