[codingdave]

I can think of a couple reasons:

1) The actual app isn't complex, not if you are only scaling to an internal audience. Most Enterprise IT coders could whip out a clone. On a build vs. buy decision, this just isn't hard enough to be worth buying.

2) Discussion apps have been available as parts of various enterprise platforms since literally before the web. Sure, some are better than others, and none of them are great. But from a value prop perspective, putting up topical discussions just isn't a big pain point in enterprises. Even if it were, Slack tends to work just as well when we are talking about internal communications. Why would an enterprise pay for another discussion service, unless it solves a significant problem in their core busines?