If there were only a way to slow down the internet connection to 1mbps or so, a lot of that instant-gratification habit-forming engagement psychology wouldn't be very effective anymore.
Even before YouTube, people could have spent 9 hours a day watching rented VHS and DVDs. It just took too much effort to form a habit based on instant gratification with that. So not many people did. And people were much more selective of what they consumed, too, which is an added benefit for mental health.
Your second paragraph is a rose-colored view of history. People simply watched television. No need to rent when you had hundreds of cable channels to endlessly scroll through. It wasn’t as curated as streaming but then it also helped to avoid the decision fatigue of streaming (and makes me wonder if Netflix and co. could reintroduce “channels” to funnel user selection and reduce analysis paralysis.)
Even something as simple as the regulation requiring the site to make it EASY to turn those things off (But give the choice to consumers via big, easy to see toggles in the right places). Rather than having them put in browser extensions.
Or we can regulate it.