Otherwise, it's pretty dumb to assert that everyone should play the same way or else they're fundamentally looking at the genre wrong.
I never understood this when people are trying to push solo play being "just as important" and not realize how that kind of throws everything out of whack. Solo play is perfectly fine...as long as it's not tied to progression. A game can't properly cater to solo and group play and keep rewards balanced because one option WILL BE superior to the other...Even in XI currently due to low population you can "solo" with the help of awesome NPC helpers, yet it still requires learning the content. Solo play in XIV usually means no difficulty and no mechanics to deal with because the content base is built around 4 man parties and the end-game content is built around 8 man, any deviation from that will throw everything out of whack severely in this game, not the genre, but this game. I prefer to duo with my SO when possible in games so I'm not against "solo/low man" but.....
Let's be honest, with FFXIV in particular the game has no horizontal growth. It has a terrible vertical growth even for a vertical progression system, if you try to "split" that by allowing meaningful solo play, you already ruined group play because NO ONE will touch an aspect of the game that is worthless. You may find it fun or prefer it but guess what? Participation speaks and even Yoshida himself stated the introduction of the Raid Finder got almost everyone (that don't sit around crying everything is too hard or they have "no time" but has plenty of time to do content with no mechanics) particpating in a sense and that clear numbers on ex primals and savage content is at its highest since Coil, which too was at a high clear rate overall compared to the Gordias mess up.
Here's why trying to add solo play progressively is bad:
Ilvl 300 from solo play - Content involves killing trash mobs, no mechanics, no learning curve.
Ilvl 300 from Group play - Content involves learning the boss patterns, the field mechanics, the ilvl requirements to meet DPS checks, Heal checks, not get face caved in by tank busters, getting the flow of battle down with your group you go in premade or raid finder.
The ilvl300 body from solo play has better stats than the one from group play - why would I do the group content when I can get the same and better rewards from solo play? Basic human nature leads you to path of least resistance, especially so in FFXIV.
I mean I get it, some people just hate group play, but there's numerous single player RPGs, some with MMO like mechanics you can play and funnily enough, people get told "this game is not for you" all the time whenever you bring up something you dislike, but don't seem to realize themselves if they like solo play, clearly, MMOs aren't for you. Solo play with it's own progression system similar to PoTD (so the only overlap at best is maybe a weapon/armor) would be cool to have, but if there's another Diadem situation where better stuff comes from doing less work, good luck convincing your players to do content that requires actually knowing how to play the game lol.
Not even saying this as a personal thing, since we all have our preferences but shouldn't the same logic apply? You can say "want more challenging content!" you get told "FFXIV isn't for you." "Want better itemization!" get told "FFXIV isn't for you", well if you feel MMOs should have more solo play..technically multiplayer games aren't for you either. If XIV has 6 million players like SE loves boast, should be no problem finding people you can click with
As far as successful MMOs go...
Unless your MMO is named Maplestory, you're not successful if FFXI can't be considered successful because it didn't have millions upon millions of subscribers. No MMO prior to WoW could be considered successful either then since all WoW realistically did was make the genre more mainstream, similar to how Halo brought in a new generation of FPS players due to being a very successful console FPS, a really fun one at that. Goldeneye still takes the crown, but Halo had the LAN and online Multiplayer eventually.