There's a huge difference between UB (as in C/C++) and nondeterminism, so I don't accept this assertion. UB in C gives no semantics to executions containing it; it is neither spatially nor temporally contained. No other programming language has such a ridiculous and program- and programmer-hostile concept. And for good reason. It makes reasoning about buggy programs a non-starter. And all programs have bugs. We debug them by analyzing their runtime behavior! Crashing immediately upon a bug, exactly the same way on every machine, is the absolute best way to find and fix bugs that cannot be caught statically.