I place little blame on the content when something like Hall of Novice teaches you imperative fundamentals to group play that goes with you from the moment you graduate HoN all the way until you play your last raid. The little blame I do place is because HoN remains optional. The other thing about progressive content is no middle ground. The closest we have is probably HM primals, but even these instances... The synced iLv is ridiculously high. A tank of this iLv can survive all three of Ifrit HM charges without a heal, so why exactly should he move from them? Especially when a sole regen will patch him right up?
I blame the community for anything other than rapid progression to be unorthodox. Despite the fact that there is no middle ground of difficulty, I still believe the casual stuff punishes players enough that they should learn to obey mechanics. But being carried through content, running it unsynced, or skipping it is going to stunt any kind of skill progression until the player no longer accomplishes things in such a way.
The way I feel is each player needs to be accountable for their own skill. How do we as humans get good at anything? It's through countless hours of practice. We practice to get better at what we are good at; we practice to get good at what we're bad at; we practice to maintain the skill we have acquired. Jump potions, starting jobs @50, rushing through content... not a whole lot of practicing going on if you ask me. Ultimately the largest skill gaps are between players that want to be best from the players that want to be the rest.