I played Synnibarr in Raven’s group in Seattle in 1992 & 1993. It was indeed the center of this threefold model. Synnibarr is in some ways an awesome demonstration of what you can get if you take the basic D&D form, and let an idiosyncratic adventurer of a DM just homebrew and build on top of it for YEARS, adding in new rules for all the stuff and every genre he wants to play with, under the occasional influence of illicit substances. It is to some extent the idea behind Blackmoor (fantasy + superscience) and Judges Guild (no limits on your imagination) taken to the extreme, with superhero stuff added in. Rave's pretension was in many ways a natural extension of EGG's comments about AD&D in the books and in Dragon.
Raven’s game was awesome fun to play in, BTW. The game system is a mess, and he embarrassed himself online trying to defend it, but he was a very talented and charismatic GM. One of the most fun I’ve ever played with.