Indeed. Anything that allows users to add their own text links or multimedia content can go from rate-g to rated-xxx in hot second or until a moderator maybe removes something. That's why I have been pushing people to use RTA [1] headers on sites instead of the silly privacy invading 3rd party verification sites. With RTA headers one could add a single header on any adult or user-content driven URL. A MitM proxy could block any URL that contains that header.

[1] - https://www.rtalabel.org/index.php?content=howtofaq#single