> but xor took a slightly lead due to some fluke, perhaps because it felt more “clever”.

Absolutely. But I can also imagine that it feels more like something that should be more efficient, because it's "a bit hack" rather than arithmetic. After all, it avoids all the "data dependencies" (carries, never mind the ALU is clocked to allow time for that regardless)!

I imagine that a similar feeling is behind XOR swap.

> Once an instruction has an edge, even if only extremely slight, that’s enough to tip the scales and rally everyone to that side.

Network effects are much older than social media, then....