.
Put together a group. Arrange a static. Allow for the fact that, ya know what... things just might not come together in a given session, and you might have to put it off 'til the next one. That's life. Guaranteed, whatever it is you're trying to get done... you'll get it done, so long as you stick with it, and don't just go into "whining on forums" mode when something doesn't go your way.
Work on something else in the meantime. It's all grist for the mill anyway.
If you're grown enough to have a life so full that time is so limited, chances are you're grown enough to realize sometimes things just don't go the way you want them to. It happens to me. It happens to everyone.
If that makes the game un-fun to play because you're unable to do things in the time-frame you want, within your schedule... then look for another game where you can. Or, just accept that, again, sometimes things just aren't going to go your way, and soldier on.
I spent a week trying to get a group for Twintania. Never did get one. Still need to do it... and I will. That's life. In the meantime, there's plenty else I can be doing.
It is just plain irrational to expect a game to deliver exactly the experience you want, exactly on your terms, all the time. Especially when you bring other people into the mix, and limited time is a factor.
But you have to work around that. You can't expect the game to change to fit your personal circumstances.
A good RL friend of mine used to play FFXI. He had a full-time job, a wife, a child and a dog - as well as all that goes with it. His play time was limited to late nights, after the wife and child were in bed. Yet, he didn't go on forums, saying "Hey guys, I'm really busy, and this game's setup is inconvenient. You should change it to better accommodate me". Instead, he accomplished far more in FFXI than I ever did - and I had all the free time in the world, outside of a full-time job. Why? He focused, he worked out a plan around his schedule... and he got shit done. He completed all the main storylines (including CoP pre-nerf), and he ran a regular end-game group... all on a schedule of maybe a few hours at a time. And he's not a unique case.
It has been, and can be done.
The first critical step to making progress... is to stop making excuses why you can't. (I don't mean you personally by that).
I see what you're getting at, but there's no point in answering. It's all hypothetical "what-ifs", based on conjecture, and non-points.
Has it been a major problem for XIV so far? No.
Has it been a major issue for other MMOs? Not that I'm aware of. It wasn't in FFXI, and that game was even more demanding of time than XIV is.
There's no precedent for it.
Again, you're discussing hypotheticals here. There's no tangible indication that SE is having to deal with "alienating" any such group. People will stay or leave on their own terms, for their own reasons.
Should something like that become an issue demanding SE's attention, then they'll deal with it as they see fit. 'til then, there's nothing even to discuss.