Straight question: why did you misrepresent what I said?
Idiomatically, "some responsibility" unfortunately isn't unambiguous. Yeah, you could mean it like how you clarified now, but if you tell someone "hey, take some responsibility for this!", that could just as well be equivalent to "hey, take responsibility for this!". It wasn't crystal clear to what degree you wanted to put it solely on the parents.
But more importantly, you ended your comment by referring to this as "stupid shit", which seems to indicate that you _don't_ think parents should be able to sue social media companies for addicting kids, that you might not even think it's worth considering, and because of that I think bringing up the comparison to tobacco and alcohol was relevant.
Seeing as everyone here has interpreted your comment in the more or less the same way, as an obvious lack of understanding around the realities of raising children, maybe it's not them misinterpreting you.
literally no one would disagree that "parents have some responsibility towards their children."