I see this as part and parcel of something we've been discussing a lot on HN lately. It's 2021, and the problems of community building are well known by now.

Spam should be really obvious: if you build a messaging medium, people will use it to send spam. It's also going to be used for harassment and other unsavory things. These aren't novel. We've seen them time after time.

There's no one solution to the problem. There are lots of approaches, with pros and cons. But it's long past the time for people to start thinking about them before they roll this out, not after. If you provide communications between people, then the way people behave will affect your customers. These things are people problems, not just technical ones, and failing to take that into account is going to cost you.