I guess the whigs were for taking power from the king, so I am 100% whiggish (this is also coming from an American who might not understand the nuances here), but I agree not all new things are better by default

(I really need to check out Heart and Spire)

I get where you are coming from, but I am sort of against this subjectivity plateau, where everything is subjective and equal. It's still worth comparing designs to see what they set out to do and how effectively they do it.

My reaction is to say that there are ways to do adventuring and dungeon delving better than B/X does, like ItO systems or even Trophy. The Grognard version of "system matters" says that there is no need to improve on the old designs, where there is actually plenty of room for it.

Yes, to an extent, this was the idea that the Forge's "system does matter" introduced into the zeitgeist. But even now, there are OSR grognards who say "system matters" as a way to gatekeep new design, totally the opposite of that first meaning

Ironically, this itself reflects certain cultures of play

Instead, culture zones are much more useful, because geographic areas have day to day interactions and end up having more coherent similarities between their cultures. So I think a comparison to TTRPGs would make sense. Mechanical similarities doesn't necessarily mean similar cultures of play

This tension is between the taxonomic and cultural. This is a bit of a problem of structuralism. In museum exhibit design, it's doesn't make sense to group artifacts by language groups, because same language speaking cultures can have vastly different culture

I also wonder a bit about if this is a chicken and the egg situation, did LARP just get big and grow into its own thing, or did it draw a line between itself and TTRPGs and then get big

So I guess on some level it seems like you're making the Ron Edwards argument, that narrativst and gamist games should separate from each other. I sort of disagree, but I wonder if you intend to make a different point from that