Why wouldn't companies just set themselves up as the exchanges in that scenario?

I don't think it would functionally change anything

Kinda like artemis but with AI?

I mostly agree, but I can also envision a situation in which you don't want the people that you're doing recognizance on covering up their illicit activities because they're listening to the police radio. A good compromise would be to record the encrypted traffic and make it public some arbitrary but fair length of time after the fact.

Ever listen to the ocean?

On Reddit, it depends on the subreddit. Some of them I don't care about usernames at all, but on smaller or more specialty/niche subreddits there actually can be a "community" of people who learn about each other

I imagine it can be similar here