I have already answered those questions in the post you just quoted but I'll rephrase. I recommend reading my previous post to get a better summarization.

Both.

Most players of this sort have already moved on, only one I remember from such an era is Aggony Duck who is still a very good player with his aggressive cavalry work.

Steam, twitch, clan forums, other community forums, new breed of players, etc. It is also the separation between the mp and sp communities.

Some additional stuff: Plus .Org has fallen off from good activity thus contributing to less people coming here for anything. An interesting thing to note, there was a a TWC analysis on other TW forums and some people from TWC note of .Orgs elitism (I remember being told the Orgahs are superior in proper behavior and politeness, funny thing I still enjoyed my time on the modding subforums of TWC discussion at IB's tavern on any sort of matter with familiar, polite people.) They see the elitism as something to be avoided too.

I can go on but imo it's a little obvious why no one comes here for multiplayer anymore. I believe it's impossible to get even a small chunk of the players to return to here, there is absolutely no reason for them to do so either.

Cheers.