The boss doesn't see that you can't properly paste a piece of code in the chat, but he wants to make sure that everyone hears him at the annual talk. He wants it to connect to the company directory, make analytics, reflect the corporate hierarchy, make announcements, etc... He sees it as a one way, top down communication tool more than peer-to-peer, and for the former, Teams delivers. Developers hate it, but developers are not the ones who have the money and make these decisions.
Still, that's a thing I miss about Bill Gates's Microsoft. It was certainly evil (Embrace Extend Extinguish, the fight against free software, etc...), but at least, they actually cared about usability and developers, not just pleasing big company bosses.