I could elaborate, obviously, but the limits of this media isn't quite fitting. Let's see how Friendica handles a long reply!
The user experience is really bad, some due to the way clients are written but some due to the inherent user-unfriendliness of the procotol, basically come down to "the user have to wait extended amounts of time" and "a basic function needs multiple paragraphs of explanation". It should, most of the time, "just work".
The spec process is broken. Has been broken for a long time now. MSCs get randomly rejected/postponed, some never get forward despite being "finished", some get accepted but never get specced. Reactions? Not in spec, and it's just one glaring example. Synapse implements stuff not in spec and other servers just look wtf was that. Element implements unspecced stuff and pours errors all over the browser console on an alternative server.
You don't think the audience is the masses and clearly some people think the way you do and it's wrong: either you target the masses or just the niche geeks, there's no inbetween, really.
Dendrite will hopefully reach alpha in months. Beta in years. Let's hope we're still around then. The Construct works already [more or less] and Timo may get Conduit working, but right now we have Synapse eating all resources and that's it.