If you use discord or slack for team communication your team communication features nothing important (ie you might as well not have it) or you work at a company that doesn't do communication security well.
Or you work at a company with no significant secrets that could potentially be shared through chatting. Priorities; why spend time and effort on some on-site solution when there's really nothing to gain security wise unless you have secrets? You won't be sharing passwords through Slack or Discord in any case, that's for a password manager, so you're really left with trade secrets, and why would there be trade secrets in a Slack channel for a web development company?
