I agree that this move is articulating enterprise customer demands rather than demonstrating greater software freedom. I don’t view this as unfortunate though. Slack is a productivity and collaboration product versus a utility like a low level database or encryption method. As such, many users and businesses want to pay for support, added features, hosting/availability/backups. It is better to have someone having to pay Slack a lot for power features than have a bunch of targeted ads in Slack. The buck stops somewhere.