I think what goes behind the scenes is just how much of the underlying proprietary messaging protocols of various IM clients are, in fact, based on XMPP. Grindr is apparently openly offering 175 to 200k in LA for a Senior Erlang Engineer familiar with XMPP.
I am also glad to learn that XMPP now has an official nifty indirect (three-point) support for Push Notifications through Apple and Google XEP-0357, although it is disappointing that this guy apparently thinks that XMPP has no need for any such service, due to an “idle TCP connection” apparently having “virtually zero impact on battery life” (he then goes on to outright dismiss it having any impact at all!).
Well, guess what, when I have just a couple of such apps installed, each having an “idle TCP connection” of its own (which obviously still has to be maintained due to the various connection timeouts, independently by each app), and I’m not even using any of them, why does my phone suddenly never survives even 24 hours of standby? That’s because it’s a tremendous waste, and relying on the central push notification service from the device manufacturer is always many times more efficient (especially since it always has to be maintained anyways, whether used by the app developers or not).