Gregory's ServerYou may know more about this than I do, but I think what I'm getting at (based upon what I have heard from others) is that I expect XMPP development was dependent upon a few large organization with funding.
Mastodon, I think, has a broader base of people working to keep it alive and building tools that depend on it. While the deep pockets may not be here yet, I think that there is a much bigger independent user base.
Does this make sense or is this completely wrong?