Why would a site that hopes you'll send them money in exchange for product, refuse your traffic if you have an ad blocker enabled? That just costs them money. Same for government forms, why would they refuse your traffic if you're blocking ads?
Best part? Trying to convince the operators of such sites that users they cannot see in their "analytics solution" are worth fixing their site for is not exactly a straightfoward job - from their narrow view, these users simply do not exist, because the tracking does not show them!