I don't know man, I multi account because it's nice not having to schedule something together with three separate other human beings every single time I want to run literally any dungeon. It's nice being able to do things at my own pace and to play with my friends because I want to, not out of necessity. I personally would rather NOT spend 9 hours running Wa Wabbit when I could spend 4; I simply don't have the available game time for it. People grow up and get responsibilities and fuller schedules. What was doable as a kid because you had time to spare no longer cuts it. I recognize that you play the game to make social connections and have fun with others, and I think that's a lovely way to play - I too think this game is about social connections and that the community is what keeps the majority of people here (what little there is left of it on Echo, even). I just don't think that multi-accounting was what killed the game, and I don't think you should go around blaming people who value their time rather than taking issue with Ankama's refusal to advertise, terrible treatment of the international community, rushed updates, blatant cash grabs, and other clear issues with the company that runs this game.
Long and short of it, multi accounting is fine as long as the people doing it still want to hang out with others. If they don't then they never would have in the first place. It's not like opening two Dofus clients at once is a magic drug that turns you anti-social.