Opting in to NSFW content is not consenting to randomly have pornography thrown at you by a subreddit that wasn’t a porn sub when you subscribed.

What the fuck, dude.

Majority of them did consent to the possibility of encountering such content. Thats the whole point of that check mark.

There’s an enormous difference between “I’m okay with content considered NSFW, like descriptions of war and so on, being shown to me” and getting porn in your main page. That check box is not an “I consent to being shown porn” button.