Pthread: Why people bother using pthread_exit?

Question

As far as I understand, pthread_exit() exactly equals to return when you need terminate a thread with a return value. When people can use the consistent way, i.e. return, to

Answer 1

If you're going to call pthread_exit a duplicated interface, then you should also call exit() a duplicated interface, since you could exit the program at an arbitrary point. You probably want to call pthread_exit() when you have some sort of error condition where you simply cannot continue. Or, alternatively, you've found whatever value you're looking for inside of the thread.

As for it's real existence, according to the documentation:

An implicit call to pthread_exit() is made when a thread other than the thread in which main() was first invoked returns from the start routine that was used to create it. The function's return value serves as the thread's exit status.

So if you did a return from the thread, or simply reached the end, pthread_exit() would be called anyway. It's the same with exiting from main(), if you return 0 you're actually calling exit(0). The function has to exist, otherwise the kernel would not have a way of determining if the thread exited.