I always found this principle odd because it offends across the political spectrum.

Every hassle the porn industry gets, the gun industry gets too, and that obviously has a very different political footprint. I'd also expect some industries with politically powerful friends (supplements, MLMs in general) to be offended by policies that put some merchants into higher risk/higher cost/higher rejection categories.

I had hoped something like FedNow would take off-- a government-backed payment rail with a formal mandate to service any legal business, so neither side could complain about being deplatformed.