My point was: GitHub as an organization didn't choose Teams willingly, and are still paying for Slack and only using Teams for video conferencing. Of all the explanations of why that might be, the easiest to land on is "because Teams just isn't that good."
I haven't used slack but broadly speaking Teams / Zoom / all of the other platforms I've used have been roughly the same, in that they all get the job of text and (usually) video communications done. Some might be a bit nicer to use than others but largely it doesn't matter which one you use as long as everyone is on the same platform.
In my current work, it’s 100% teams. I’d be doing in my heels over swapping to teams as well if I was GitHub, using it for any kind of text communication is such a massive downgrade.
HN of all places should know better than to believe that people using one thing instead of another must mean the other thing is worse.