Wow, thanks for the warning that Couchers bans naturists. I am aware of many unique and beautiful experiences by naturists hosts. It’s disappointing that Couchers would want to eliminate them.
Self censorship resulting from pressures from the likes of Visa, MasterCard, Google Play and Apple's App store when the law doesn't forbid it. This is the problem when the world is run by monopolies. Laws don't mean anything, companies effectively make them.
I'm pretty sure payment providers aren't the reason why Couchers decided to ban those offerings.
There are other reasons to not want to deal with issues resulting from non-traditional lifestyles beyond that pressures from payment processors and pretending otherwise is a little silly.