It’s a personal thing, but I put more credit in logic than numbers alone. It’s really easy to point to numbers and draw the wrong conclusions. And I’ve seen a lot of misleading graphs in my day. For the record numbers are important too and you’re right we don’t have those. But I don’t think that you can’t make a damn good hypothesis without them. So yes, I contend that the majority of the current users joined, if not at launch, sometime before Mists of Pandaria. Can I prove that? No. Do you want to dismiss that hypothesis out of hand because I can’t? Your choice to. I’m not here to tell you what you should believe, just share what I believe.
But I think my logic is pretty sound and given the sheer size of this thread I think it’s safe to say the results are speaking for themselves. I’ll grant you I’m making more than a few leaps, but I feel safe in those leaps.