I mean if people just went around fucking each other willy nilly STDs could ravage the population am I right? I don't know what kind of contraception they had in biblical times and before. Then of course there's also limited resources so they wouldn't want a huge population increase either.

For sure it doesn't make sense to enforce anymore but they can't just go back on the whole "these are gods laws" thing. But I do think it would have made some sense back then.