I heard the same thing, but apparently a recent patch (released this year) streamlined ARR into something more palatable. Let's see what the active players in this thread say...
You ain't gonna be healing shit. Ultimately, absolutely every class in this game is DPS—and the only "complexity" comes from the artificially convoluted button-mashing routine of your DPS rotation. "Healing," "buffs," and "debuffs" end up being virtually unnoticeable window-dressing for your DPS rotation. Crowd control, true support classes, and other subtleties of MMOs past don't exist, as you'll discover when you're required to show the results of a DPS test to get your "healing class" into endgame raids. As for the raids, their difficulty stems entirely from Simon Says-style gimmicks that must be memorized.
The quest grind is absolutely terrible even for people who have a fun Discord channel to chat with, let alone hermits. You'll be doing most of the grind solo regardless. If you actually read the hilariously bad quest text, you'll only prolong your suffering. Squeenix may claim that this has improved, but I promise you it hasn't, except maybe superficially. Get your wallet ready.
I did the grind, from beginning to end. It was unreal, fucking
unbelievable, and I was so astonished that I just had to keep going. At the end, I was driven only by a sense of irony. I never thought that a post-WoW-era MMORPG could have so much solo grind, and I say that as a release-year FFXI player. Somehow, I finished it; I must have been ultra-bored that year. And by the way, I stole all the good people from a mega-guild on my server, founded a new guild and Discord server, camped with my new guild to nab some fancy player housing, and we all (eventually) played end-game content together for a while before I called it quits. I've seen what the game has to offer.
That said, I'm not an active player, so feel free to disregard this. I'm sure this eleven-year-old game has changed dramatically in the past two years—and for the better, as aging MMOs so often do.