Those who use self-hosted chat platforms, why not Slack?
We’re currently using Mattermost as our self-hosted chat, but outside of cost savings, there doesn’t appear to be a good reason why we don’t switch to a SaaS like Slack which has more features, integrations, better app, etc. What are your reasons to use Mattermost/RocketChat/other tools instead of Slack?
I don't believe in using proprietary software simply as a matter of principle. There are a handful of places in my life where I do out of necessity, but I try to avoid it as much as possible.
I use slack and have never used those alternatives you’re talking about but there is a case to be made that self hosted tech offers better privacy.
If you are in a regulated environment, it's likely because of either compliance or security concerns (I'll note that while Slack has HIPAA-compliant plastered over its website, the last time I checked only the Slack Enterprise was actually HIPAA-compliant).
In my last role we used Mattermost for a while, and the incubator portion of the office used Slack. Everyone wanted to use Slack, but it was mostly a brand/clout thing. We ended up on slack and it was a virtually identical experience.