I meant that you can't rely on platform/implementation specific behavior to save you. It's the worst of both worlds: you don't get performance benefits of UB and you introduce a disaster waiting to happen once your code runs on another platform or is compiled with another compiler.
I know what UB is. I think the idea is brilliant and saves millions of dollars of burnt coal every day. Sometimes security matters more and then you compile your code with every flag/sanitizer you can find to exchange performance for security.
Performance benefits of UB aren't obvious, and even if they existed, it's not obvious they are a good tradeoff. It's not only security, but any application mildly interested in correctness. Which leaves gamedev as the only consumer of aggressive UB optimization, and with the advent of online gaming even those might be more interested in security.
I know what UB is. I think the idea is brilliant and saves millions of dollars of burnt coal every day. Sometimes security matters more and then you compile your code with every flag/sanitizer you can find to exchange performance for security.