Yeah, I made a half-hearted attempt at running a play-by-post game here. The players were brand new, so I tried using a rules system that was more streamlined and better suited to text than D&D. The trade off is that if anyone has played D&D before, learning an additional system is unappealing no matter how simple.
The compromise might be to start with the shell of a standard rules system. Then handwave away most parts of it in favor of narrative descriptions.
Not long afterward, the Tapas Roleplay Cafe thread (which was entirely freeform) really took off, so there was no longer much need for any other roleplay thread. It got so popular that I saw one user express concern that the forums might turn into an exclusively roleplay website.
I currently run a couple of play-by-post games in Discord. (Cyberpunk Red and Star Wars D6) I'm also playing in a couple of others, also on Discord. The best game I ran last year was a roleplay of The Price is Right, no dice involved and only show-derived rules. I see no reason why a dice-driven game couldn't work here in the Tapas forums. You'd just need a schedule (one post per day minimum has always worked for me) and a handful of invested players who actually come here reliably.