If evaluating this for business I’m not sure I’d want to trust company confidential chat with Facebook.
Annoyingly it might get more adoption though. I know some who don’t want to use Slack or other third party team chat tools and would rather just use Skype(!) as it’s familiar to them (even though it doesn’t do the job). Facebook being familiar to people may make it more popular.
I’m trying to push Microsoft Teams where Office 365 is used as it comes with it and seems pretty good. As you’re paying for 365 I trust MS more to not be trying to monetise the conversations than Facebook.