If people wanted to do this theyd be self hosting xmpp servers already. No one wants to write and maintain the code and infra for things like this, you are grossly underestimating the effort involved here.
No no it makes sense. Hypothetical scenario: I, a high-level employee at a company just convinced my boss (or did we convince each other?) to spend $30k/year on Claude/Codex enterprise licenses. So far, the productivity gains have not been there and we're starting to sweat. So, I propose to my boss to build an internal version of $SaaS and call it a win. Galaxy brain.
Now some IC somewhere in the company who is at the end of his rope and sees the company as a dead end, sees an opportunity. Why not advocate for this project, get real experience building something greenfield in a brand new domain, strengthen their own resume, and finally have a way out of their strut? It's not like they're gonna stick around maintaining what they built.
Most people using Slack, Teams etc. and especially those making purchase decisions have no idea what XMPP is and what it's capable of. Heck, even Facebook used to federate XMPP until they decided to go proprietary. Not in the interest of their users, but because it makes the most money for its shareholders.
I don't pay for slack any more, I just picked the price of their enterprise plan. Large users probably get big discounts but it doesn't matter, the cutoff where this makes sense financially is probably around 4000 employees even at $10/seat
The article mentions some sort of legal audit reasons that the author is of the opinion that any reasonably sized company needs. These features are apparently only on the expensive plan.