The problem with FB: Workplace is that it’s Facebook. In the area of privacy, security and trust I believe that is just to much negativity surrounding them that companies (who are often paranoid entities already) simply won’t trust them.

Your reference to Google Apps is interesting though, but I think the general perception of these two companies is different enough to make Google Apps more acceptable to a lot more companies.

Shame really, as I think this would blow tools like Slack completely out of the water.