I'd put the Rules Cyclopedia and Hackmaster in the OSR category (and the Cyclopedia as core to some gamers there I know). So... I think we'd need to talk specific games and artifacts to reach full agreement on the level of Ludus running around.
I think there might be some edge cases of OSR books with a lot of rules, but even in those cases the vast majority of the rules are hardly ever referenced in play (Hackmaster might be an exception, I haven't played that). I don't think I've ever seen a DM in an OSR game look something up in the rules, apart from spell descriptions and things like that.