You go out in FS because Rutherford was a (door to door) book salesman and that's how he paid for college. He didn't know how to do anything else and he needed to make money.
The 70 Jesus sent out were all male. There is only one account of him doing so. The rest who went out and about did so because not many knew about Christ; their sole purpose was to tell everyone about him.
FS is irrelevant in most countries today because people already know who Jesus is and what he did. They're waiting around for his second coming too.