forking but not exiting

It is normal for the child in a fork() to call exec() or _exit().

Are there any realistic scenarios where the child might return from the function that called fork() instead?

void foo() {
  pid_t pid = fork();
  if(pid == 0) {
     ...
     return; //<-- the child is going to unwind the cloned call stack
  }
  ...

So what legitimate uses are there for a forked child returning? Are there any standards that govern this?