There are quite a few different groups within Mozilla that are accustomed to and comfortable with different communication platforms. For chat, it's mostly Slack

There are quite a few different groups within Mozilla that are accustomed to and comfortable with different communication platforms. For chat, it's mostly Slack vs Matrix. Everyone around me will roll their eyes and grumble if you suggest using Slack for anything but very very clearly company-internal stuff. But other groups "just use Slack" and don't think twice about it, so are a bit confused when we demand to know why they're only on Slack. I guess few large-ish companies have managed to keep their communication platforms rationalized and consistent. It's more important for Mozilla to stay open than it is for most places, though.