Your claim that XMPP is a bandwidth-hungry, but in my experience, if XMPP based systems drain battery and consume a lot of bandwidth, then it's because of a poor implementation and design decisions, and not because of the protocol.
- There was no real alternative to the web. - More importantly, ie6 worked for the end-user. It only sucked for the developers.
MSIE worked for most people. The devs suffered how bad it was, but the people didn't see that because most of the web was designed for it. That's the kind of power you get when you are lead in marketshare. We see that nowadays with websites that only work in chrome (though it's less of a problem, chrome is a lot more open to standards, and the engine is open source).
Concerning branding, I still see a lot of people that think the internet is that "e" icon on their desktop. Other people think chrome is the only gateway to the internet. It's the same situation as when IE6 was the lead. People don't know about alternatives, or don't care. Either way, if their "internet app" sucks, it's generally that internet sucks.
[0] Using https://www.w3counter.com/trends as a source, don't know how accurate it is but it does match my memory of how it all happened.
That was largely related to large install bases in corporate/government/educational institutions where legacy requirements (e.g. we built/bought this IE-optimised internal mission-critical web app, and it shits its pants in other browsers).
> It's only when chrome started doing very aggressive advertising that people started to switch.
In 2010 Statcounter and W3 counter both give MSIE ~50% and Firefox ~30%. There was huge shift away from MSIE long before Chrome existed, and longer still before they started using shitty tactics to 'encourage' people to change from other perfectly functioning modern browsers.