I'm not oppositional to this ab initio, but is there any good evidence this will work? I see the pressure on the demand side: the parents concerned with the never ending feed. What I don't see is some A/B testing, we checked, and a "thats all folks" feed end makes people stop and go away.
Some of my views in reddit do that. "thats all folks" And .. I just go to another subreddit. So I can't say this ends my never-ending scrolling. What effect it's having at scale, I'd want to see some numbers.
Some things which are marginal are still worth doing. Turning the internet off at 9pm might well be a good idea. Or Albianian 1970s "no TV on mondays" (not sure it really was a thing, but I do remember the dot at mightnight after the national anthem on the BBC)
One might argue the social media companies already did that research before adopting infinite scroll.