I'm actually not so sure I agree with this. Because progress was slower, and itemization was horizontal, it was quite difficult to actually be truly left behind. I know I took regular breaks from my end-game LS for months at a time, but when I popped back in, guess what? They were doing the same runs as before - just with different people needing the loot. I always found it quite easy to slip back into things, particularly since FFXI offered far more flexible group sizes.
In contrast, FFXIV's rigid construction of end-game content and rapid pace of itemization make breaks quite difficult. If I quit FFXIV for six months, I'm going to (a) lose my house; (b) no longer be sufficiently geared for Savage / Ultimate content; (c) no longer be familiar with the mechanics in the current batch of Trials and Raids; and (d) likely find my spot filled by someone else if I happened to be part of a static group. That's a pretty stiff penalty for taking a break, much stiffer than anything I can recall in FFXI.
I'd also point out that FFXIV's progress is less memorable for a variety of reasons. Part of that is the solo'ability, and simplified grouping, but the game is overall just too convenient for its own good. The impact of travel conveniences alone is mind-boggling: for virtually no money whatsoever, you can get to literally any point of the world within five minutes. That is insane - and it reduces the scope of Eorzea in a way that never happened with Vana'diel. Then there's the meaningless and trivially easy gear repairs; the easy availability of Gil; the incredibly solid gear gifted to you simply for progressing in the MSQ; the smooth as silk path to 70 wherein you don't have to grind for XP at all - just complete quests. Even crafting, which is an area of FFXIV I well and truly love, is too easy: I can HQ any recipe below 65ish with virtually no effort and no HQ ingredients, and all but a handful of ingredients are trivially easy to acquire, in bulk, within a few days.
All that convenience has a cost.
Very very much this. I mean, FFXIV event kept the same races, roughly the same city-state theming, dozens of the same models (many of which continue to be introduced today, like Antlions in Stormblood)... it never stood on its own. I will say that XIV 1.0 had its own identity, but it was a bad one.