It is an assumption, but its a plausible one because we see this trend in MMOs that operate more like WoW than FFXIV in regards to a story based system. You need to consider how the game's core design and player base pressure new players to do certain things. What you see in MMOs like WoW is new players are encouraged to power through content to get to end game. Low to mid level content is over experienced. You dont even get through all of an xpac or area before jumping to the next xpac areas. This is further reinforced by player attitudes - "Fun happens when you get to current content. Just power through everything else. You can read about it later." Almost all questlines in WoW are optional...and most of them are left undone and bypassed by a large swath of the newer players in their efforts to 'catch up' and 'get to the fun.'
I feel this has two knock on effects: You create a bit of a disconnect between older and newer players, as the only thing they can kind of bond over or understand is current content. Old timer players know about things like Barrens Chat and mankrik's wife. Newer players dont know jack about that except if its explained to them, seen the memes, or the devs give you an 'easter egg' so you feel like you can be a part of the joke. But it's not the same as experiencing that first hand. Youre not in on that cause you never went through it.
The other knock on effect is if you train your player base to prioritize "get to end game to have fun", they will expect just that. So you will need to divert resources away from things like MSQ and minimize it for the sake of "Get to end game for fun." It changes the focus of the game from the journey and story to get to the raids and end dungeons. I think this model has it's strengths, but I do not think that it will be beneficial to content like FFXIV. Rather I think it will actually damage the game long term.
Pick your MMOs by what you want: If you want an MMO where you pick and choose what you do and its like a buffet that revolves around whats most fresh, WoW is a solid place for that. If you want an MMO thats more about the journey and story focused, FFXIV is where its at. Two different models that have two different core focuses.
This is where we do differ. While dungeons have you join up with randoms you may never see again, that isnt something specific to FFXIV, but MMOs in general that have a dungeon queue system. In fact some of the points you point out are not unique to any MMO - but rather just part of the genre (and gaming at large). But I digress. Point is the bonding point isnt about dungeons, its about the experience of the story. When people can comment about parts of the story and old and new player can understand the sentiment. You dont get that in WoW. In fact, both have some similarities in the ideas behind leveling from a mechanics stand point - Go out complete quest. Youre not typically doing these quests with other players right there, but more solo in both instances.
However, the choice difference is old and new player do the same primary quest, meet the same primary NPCs, do the same cutscenes, experience the same story. If youre a savage player or a newer player, youve had to go through the same MSQ trials and can relate to other players who have done it. It's great watching new players discover aspects of the MSQ and characters. You simply do not get that experience with wow. In WoW, you pick which quest you want, often revolving around run to a hub, pick up all the quests til you out level the area, and move on and discard any quest that no longer gives you experience. First time players may read some of it, but again, peer pressure usually just gets them to simplify the process and accept quests and move on. It creates vastly different experiences within the player base, and the speed of that leveling pushes you through zones well before you can really get to appreciate that content. Sometimes you completely skip areas cause it's to low level. In fact, FFXIVs design wiht MSQ actually discourages you from running from hub to hub just picking up quests.
There is very little unifying player experience at low to mid levels. And htats fine. Again, focus is important. WoW decided its all about whats hot and new, the old stuff is just a formality at best. FFXIV is about the journey, play through the entire experience from lvl 1 to lvl 80, and then 80 has things to do once you get there (like any MMO).