I think it started from a strong place, but in my view System Matters hasn't survived completely. The way I see it, the Story-Games incarnation of System Doesn't Matter is "techinques". Basically people see something, say "Oh, that's a technique that good players/GMs use", and then think it's something they can bring to every game. So take Improv Acting -- the "rules of Improv" are themselves a System in the Forge sense, but if someone thinks that the "rules of Improv" are just a thing that good players do then they'll start bolting those mechanisms onto whatever system they're nominally using. So, for example, they might be keeping their character in a much more pawn-type stance than the game expected so that they'll be able to "roll with" whatever the other players throw at them. At least I think that's what happens, with at least some people.
RE: AprilTTRPGMaker Day 29: Your community.