> But a thread can still crash in its own due to unhandled oom, assertion failures or any number of other issues
That's not really true on POSIX. Unless you're doing nutty things with clone(), or you actually have explicit code that calls pthread_exit() or gettid()/pthread_kill(), the whole process is always going to die at the same time.
POSIX signal dispositions are process-wide, the only way e.g. SIGSEGV kills a single thread is if you write an explicit handler which actually does that by hand. Unhandled exceptions usually SIGABRT, which works the same way.
** Just to expand a bit: there is a subtlety in that, while dispositions are process-wide, one individual thread does indeed take the signal. If the signal is handled, only that thread sees -EINTR from a blocking syscall; but if the signal is not handled, the default disposition affects all threads in the process simultaneously no matter which thread is actually signalled.