Regardless of how you classify them, nobody was ever going to figure out how to sideload a jabber client onto their flip phones or iphone 1.

And that is kind of the thing. Maybe Google got a larger market share of the IM market (I assume AIM was still dominant in the US and ICQ in the rest of the world) by using XMPP but better. But the market got wiped out by SMS and imessage and now is mostly shared between (depending on your country) whatsapp, line, and the imessage.