Comment by Arathorn

They're typically operating in private or semi-private federations, and so aren't so worried about spam/abuse issues like the one in question here. They may also not care as much about serverside metadata footprint (or indeed they may actually require serverside metadata in order for the server admins to enforce who can talk to who).

As a result, the popularity of Matrix in public sector has resulted in focus there - which is somewhat different to the expectations of folks looking for a Discord replacement or a privacy-at-any-cost solution.