I see the counterargument, but we are still pushing companies onto the public that are losing copious amounts of money. Part of me wonders if we aren't witnessing the irrational exuberance before the (cyclical) fall.
Thanks for the mention. Increasingly we see mention of "Slack or Mattermost" as part of DevOps stacks. In my mind, the space is growing quickly and there's room for multiple winners.
I'm excited about having more and more functionality people love available in an open source alternative.