It's bizarre that it's legal for me to look at pictures of a naked person, but effectively illegal to use technology to do so, just because advertising is subject to the whims of a moralistic and prejudicial minority.
The phrase 'effectively illegal' does not make sense for two reasons here. First, looking at naked pictures is different from hosting them to allow others/public to view them. Second, just because something cannot be monetized easily via ads does not mean it is effectively illegal. You could also just direct charge for it, like a lot of businesses do. Also, there are a lot of adult service advertisers, including Viagra and the like that monetize porn sites.
It's really just the moralistic people pressuring advertisers. Minors can find a way to get their hands on a Playboy, but we don't stop selling Playboy in shops just because that can happen.
People interact online through a select few pieces of tech: smart phone apps, Facebook, Instagram, Tumblr, Twitter. Just saying "adult sites exist" is like telling people to drive over to the wrong side of town and shuffle into a seedy porn theater. The malware-laced pop-up ads, and the lack of creative, multifaceted sexual expression, is what happens when you effectively banish a form a culture from the commons.
