>>96568681
What you've suggested is just an analog version of the play by post roleplaying forum, and these almost never work, too many people pulling in different directions to actually get a coherent game going most of the time.
Play by post in real life is perfectly doable. It used to be a thing, in fact. Play by mail. And later, play by email. You need not involve more GMs to run single (or even groups) of NPCs. You would have difficulty finding GMs willing to do that, anyhow.