Yeah I'd argue these problems happen because people don't take advantage of RAII (maybe because they don't like it or their language doesn't support it), and th

Yeah I'd argue these problems happen because people don't take advantage of RAII (maybe because they don't like it or their language doesn't support it), and then forget/neglect to do the proper cleanups at the correct time. You want to design things so that they encapsulate their correctness by design. For a thread, that means joining it on destruction (because that should happen in general). For a mutex, it means not unlocking it on destruction (because that signals another part of the code is actually incorrect). For lock guard, it means unlocking on destruction. For files, it means closing them on destruction. Etc. You can't just reduce everything to "always" or "never".