I’m quite terrible at the physics aspect of all of this, so pardon my wording.
Anyhow, as referenced from here:
If human skin can absorb (or deflect, or sustain) a fairly large shock of static electricity, what exactly could have brought about this particular trait?
I find it hard to believe that somewhere a million years ago, humans were being literally shocked out of existence at every rainstorm, leaving only the lightning-resistant humans behind 
It’s not a design criterion.
It’s just a side effect of the way skin is made - dead cells don’t conduct current very well.
Having extremely conductive skin would be much more unusual - most things are poor conductors of electricity.
As beowulff says, most things, especially organic compounds, don’t conduct electricity very well. For skin to conduct electricity well, it would have had to be positively selected for.
Skin is a tough coating designed to protect the body. It should be no surprise that it might protect against other things than those that were present in the environment millions of years ago.
Take a hit form two different tazers at the same power/voltage. The barbed ones are a lot worse than the contact ones. Or you could just take their word for it.