This website contains age-restricted materials including nudity and explicit depictions of sexual activity.
By entering, you affirm that you are at least 18 years of age or the age of majority in the jurisdiction you are accessing the website from and you consent to viewing sexually explicit content.
The funny thing is, I’m nearly certain that it’s opt-in for their benefit (i.e. legal reasons) and not because it benefits the content creator, because it really doesn’t benefit the content creator at all! “Here’s my work. Do what you like with it, and don’t worry about paying.”.
I suspect any time Google gives you a choice about anything, especially anything regarding data, it’s not for your benefit. With that in mind, you’re likely right.