I work at largish company (13k employees worldwide), and a couple of years ago there was a fair amount of Slack (admittedly mainly free tier) being used ad hoc

I work at largish company (13k employees worldwide), and a couple of years ago there was a fair amount of Slack (admittedly mainly free tier) being used ad hoc around the company. Then word came down from up high that the company was standardizing on a single chat platform and that platform was Teams. Now there is basically no Slack being used (and certainly no paid Slack) any more. The main argument was that Slack for 13k employees was incredibly expensive, while Teams was 'free' and already integrated into most of their infrastructure.