It's definitely a footgun, but the compiler isn't doing weird stuff because the assertions can be disabled. It's doing weird stuff because there's UB all over the place and it expects programmers to magically not make any mistakes. Completely orthogonal to this particular (fairly minor IMO) footgun.

> I’ve worked as a C++ programmer for 12 years and I’d say it’s probably 50/50 in practice how many people would spot that in a code review.

Spot what? There's absolutely nothing wrong with the code you posted.