It was a real sad day when Facebook and Google decided that proprietary was the way to go...
The writing was on the wall before that, though. WhatsApp was eating everyone's lunch and Facebook / Google wanted to move faster and own the messaging space.
WhatsApp didn't exist yet
Re:Easy XMPP: What are we doing here?
by ariwilson on Wednesday January 18, 2017 @08:01PM
(#13432041)
WhatsApp has existed since 2009, which preceded Google Hangouts by 4 years.
Afaik facebook was designed to be a closed walled garden from the get go and never offered interoperability despite using xmpp at first.
Google gtalk predates facebook and happened at different times, IIRC the change to a closed chat service was a reaction due to facebook abusing the openness to scrape contacts.
What kinds of skills would a volunteer need to be able to contribute?
What skills you have are laregely irrelavant; just find something that annoys you personally about [your favorite client here], dig in, fix it, and send in a patch. Or, if you're not a developer, use whatever skills you have, mock up a way that a UI component could work better and send it in, or write documentation, or simply file bug reports. Everything helps :)
[0] http://xmpp.org/extensions/xep-0375.html