Consumerization of Enterprise is real - people don't want work to feel like work. Even Slack is more of a social tool than a work tool [1]. So, I think that the key to building a great work-focused tool is to start on non-work use cases - such as social groups.
Looking at Twist - I don't think it emphasizes usability, users in multiple workspaces, quality notifications, easy onboarding, and group discoverability. Take a look at the nav - it's built for hundreds of people, but groups will start with far fewer than that, and churn before they grow. Plus, it's entirely a logged-in experience - how many beloved forums are logged-in-only?
Twist is a good tool for certain uses - but I'm going for something more generalizeable.
[1] https://www.newyorker.com/culture/cultural-comment/slack-is-...