There’s no question that certain types of adult content, not restricted to hardcore porn is harmful…we know it is.
It’s not “we deal with groomers OR we deal with harmful adult content…OR we only regulate popular streaming sites. We can do all of the above. We certainly don’t just throw up our hands and say “it’s not profitable to protect our children” (not what you’re saying, but rather what’s happening).
The way regulators are currently dealing with age-gating - say, in Australia - isn’t what we need to do. That certainly empowers groomers because there’s zero expertise or thought out into it: it’s an ISP-friendly virtue signal that attempts to preserve profits while making Boomers feel like something is happening.
I don’t have the answer…but I DO know there are a ton of answers that include actually attempting to study and regulate all addictive content, including adult content - ie content at the hosting level and requiring that providers and purveyors regulate their content with actual humans. We can never “win” the war if the status quo is automated moderation and profits above protection.