I saw a related aspect of this years ago trying to incubate a professional sub-community. It wasn’t a huge group (thousands of people, not millions) but important and long-lived, and the SE community was active, but it was closed for not being active enough.

Years later, that conversation still happens but not on SE since everyone got the message that mods only care about advertising metrics. That’s a common business decision but it seems short-sighted for what SE wants to do.