See, this is one of those things that always makes me laugh.
You have an opinion that "AD&D was not rules light" but that opinion is built around your particular set of experiences and how you play(ed) AD&D. It is entirely subjective.
AD&D is rules light when compared to WotC era D&D. PCs have limited capabilities, the rules are straight forward, and while it relies on charts a lot, those charts aren't complex. Where AD&D gets "rules heavy" is when people read Gygax's DMG and fail to understand that everything in it was an experiment and an optional rule. It was a collection of Gygax's thoughts on specific things. If you CHOOSE to integrate everything from the DMG into your AD&D campaign, of course it is complex (and at times contradictory).
So, no, saying "a system needs to be light for it to be good for dungeon crawling" is not the same as saying "AD&D isn't good for dungeon crawling." That's just you interpreting the statement in a way that allows you to be offended and feel attacked.
Congratulations, I guess.