Team communication tools don't suffer the same network-effect downsides to switching that other social apps do. The decision to switch can be made by one person. Everybody else is responding to a mandate.
* There's going to be a lot of discussion and consensus building. Most of the team is going to have an opinion on the subject.
* Setting up new accounts for team members, teaching team members how to use the new tool, and change management all take time.
* Most teams have integrations within their chat apps, these will have to be switched or re-implemented to use new APIs.
I think it's fair to say that most team tools have good moats. The longer the team has used a tool the stronger the moat becomes.