I think if you get older, start working, have a family, children you will realise that wow is just a game and you just cant afford sitting in it every day for 4 or 5 hours to experience endgame content.
It is natural that more and more people demand solo content at wow, look its almost 10 years! 10 years ago people went to school, did maybe study but today they dont have that time anymore.
Should they now all leave the game?
LFR, Scenarios, LFD are tools that allow players to experience the game and so far those that are younger and dont have thoese responsibilities in RL still own the game big time. You get the best loot, see the most content etc, so I would think that you could leave those with a strong RL atleast a tiny bit of the cake, dont you think?
MMO doesnt automatically imply Raid content only, or guild content only. A good MMO today does give you the chance to log in and do stuff. No matter if its a raid, dungeon, scenario or quest chain, it just needs to be instant.
I dont know how long you had to wait for 3 men scenarios, havnt done them yet. But I guess it is like LFR, it takes too long. As a tank you wait an hour at LFR, no working person can do that.
Socialising is what we humans do, but it does not automatically mean looking for like minded players for hours and this is where most MMOs still struggle today, I disliked LFD, LFR once and what it brought us, but I am also glad I can use these tools now and so I am happy to have a solo dungeon (didnt do it yet though).