Its not so much that it destroyed the social aspect because it didnt of course, its simply that it was yet another mechanic which reduces, not increases, social activity which is surely the entire point of an MMO, otherwise might as well play offline. The original pre 2000 MMOs understood that but over the years the socialising got more and more watered down until you were lucky to get 1 word from people. Which is a pity, especially given that the entire multiplayer RPG genre is the offspring of pen and paper RPGs which were enormously social things. Pity really that so many MMOers lack the desire to actually communicate with other people. I'm still in contact with people I met in MMOs 25 years ago, we've flown around the world to several countries to all meet up. Been great...but something the "heya....cya" brigade miss out on.
It did massively destroy social interaction in WoW.
Pre dungeon finder you would spam Dalaran looking for people to go to Halls of Lightning Heroic, someone whispers interest you ask what they need (Epic 2h Axe woop) check class doesn't clash with yours etc and invite them. The run goes smooth you ask if they want to go again tomorrow when HC resets and add them to friends. TP back to Dalaran find another grp possibly add another friend if run goes smooth.
Few days later your sitting in Dalaran running laps and bob from HoL whispers if you've done HC ZD and if you wanna go, sure why not badges at least, maybe do some of the Heroic achievements for the drake mount. Another time Legolas from VH you ran with last week wants to run a few heroics.
Maybe you ran some BGs with these people, do some raids even. These things were very common back then.
The problem was that WoW pre Cata wasn't casual friendly but it wasn't for casuals, you needed to put in the time, and if you did you were rewarded with potential friendships. You could log on and have multiple people insta spam you asking to do things. So obviously this was my own experience but if it was for me I'm sure it was for many more.
Dungeon Finder allowed casuals to play WoW but took things away that were important to the games existing ecosystem. DF reminds me of Halls of Reflection and randoms dieing on the waves before the first boss and groups falling apart. Not all of them, but group fails ramped up significantly. People that put in the time also stopped adding people to friends list because you queued up to the conveyer belt to repeat heroics the next day. You still made friends, but they became much more confined to your own raiding guild.
