> I'm going to go on a limb and say that the intersection between "people who don't trust the stock client" and "people who don't know about the stock openvpn client and how to set it up" is very small.

I would say the overlap is actually quite big between that. People who don't trust the PIA client would be the ones who know or are able to find alternatives. It's just that the former group is insanely small as is.