I read somewhere that the old, original Afghani way to make hash was for folks to basically fondle the buds until their hands were covered in the sticky goo and then scrape it off.

As for the thc sticking to your fingers, when breaking it up, and decreasing the potency of the weed. Sure, it probably does, but it would probably be something like a 0.000000000001% decrease so don't worry about it.