I rarely prune my melons. When when I do, it's because they're
intruding on another space. What you heard is an old wives tale.
My melons get ample size and yield, without pruning, and I'm also
in zone 8.

Pruning off vine and foliage will reduce yield and sweetness period. You can't cut off the sugar producing leaves and expect more or sweeter fruit. That's like expecting your car to go further if you siphon gas out of the tank.

Got it, thanks.