> The only insane thing about UB is that compiler writers took what everyone understand meant "the compiler emits what it emits and you get what you get" and turned it into "since it's undefined it means it can never happen so we can delete your null check".

This is the bit that seems insane to me. Some of the behaviour of C/C++ compilers when they encounter undefined behaviour seems less like 'this is undefined, we'll just do something vaguely reasonable given the context/produce an error' and more like 'ahaha, the user has fallen into our trap, lets fuck them up'.