I reckon the best "theory" discussions I followed back in the day on The Forge or Storygames forums or more recently on r/RPGcreation are all tied to actual play experiences and/or a focus on practical application. The focus on the real world humanised discussion and prevented some of the worst behaviors.
Viewing post in Can the RPG Theory well be un-poisoned?
I think being grounded in the real world of play does tend to lead to better conversations than pure abstractions. While I think the Forge's later strategy of "You're only allowed to talk about Theory via AP posts" was flawed (not least because Forge-style AP posts became a genre with their own social dynamics around them) I think the idea was well-intentioned. Trying to come up with actual examples that illustrate ideas, or ways you think you could test your ideas out, probably helps keep things from spinning out into styles of interaction that can be more emotionally charged.