Leveling has no relevance to Endgame,
A) There are players in WoW and FFXI that never did any serious endgame at all but just leveled and were part of the community. They still played for years, heck you can look at players right now and can you honestly tell me the majority of them are end-game geared? (as in not serious endgamers with all 119 gear).
B) Leveling is supposed to be the hook, once a player is addicted they will put up with far higher levels of rubbish later on. This is why you don't start by annoying people if you intend to keep them long-term.
In the past the community was a major part of what kept players around on FFXI, that is NOT the case anymore. I can speak personally that when I had problems with my AF quests, getting party invites, getting optical hat, getting missions done it was the other players and community, the living breathing world that made me put up with those annoying road blocks. There is no living breathing world anymore so it's more down to the developers making content work properly and flow well enough to keep you interested.
Also almost every single endgame player needs baby feeding, you know when almost all the endgame players started doing endgame on ffxi? When BG forums became a hub for sharing strategies. You know what would happen to endgame linkshells if the wikis and bgforums ceased to exist? You think all these endgame players would talk to every npc in the game, and try all different strategies to see if things work?