Back in the day, like many people then, I had a couple of different accounts across multiple messaging platforms. 2 domestic ones, couple of international ones. It was a fun mess but people were tired of running multiple apps and so loads of multi-protocol apps were developed.
Usually messaging protocols were simply reverse engineered and some apps also used plug-ins so that niche protocols could be added by community. Some also did gateways that translated proprietary protocols to XMPP.
By the end of that era many platforms opened themselves up with XMPP. It was nice because most of those multi-protocol apps didn't have to support as many different platforms explicitly.
But that's about it. I had a Google Talk account too and found it cute that I can use it to add my friends on other platforms. I was a nerdbut barely knew any other people that were utilizing it. Realistically it didn't make any difference because you still had to use multi-protocol app for the ones that didn't open.
Soon platforms that were never on or barely on XMPP started to take over. Messenger was the biggest in my country and it was always a PITA on third party apps.
Google Talk doing a rug pull on XMPP didn't to anything meaningful to XMPP itself. It was never that big and simply remains a niche to this day.
I too get an impression that a single article on XMPP Gtalk drama made round on Fediverse that many made their opinion solely on it.
Look into OpenCore Legacy Patcher. I updated my GFs 2012 Air to Ventura and it's running okay. A bit clunky around MacOS updates since you have to specifically run patcher again to get graphics acceleration again but otherwise fine. It's definitely worth it for security updates.
https://dortania.github.io/OpenCore-Legacy-Patcher/