No, it's only their responsibility to read and follow the manufacturer's instructions. That's very different from having to independently research and identify hidden or unknown dangers.
When they are explicitly stated in the user manual? Yes. That's part of being a responsible adult.
Your examples are of cases where the seller is not telling you material facts about the product. (Unless you think that toy makers who put lead in their toys or bakers who put arsenic in their muffins actually do state that explicitly somewhere in their "fine print". Which of course they don't.) That's a completely different situation, which we already have a name for: fraud.
> That’s a ridiculous approach.
No, what is ridiculous is to make a completely invalid comparison as though it were a valid argument.
> there’s no evidence it increases failure by any meaningful amount
A number of other posters in the thread have posted evidence to the contrary. Your naive confidence in the power and goodness of regulations is sadly misplaced.
You bought a toy for your kid that happened to include lead. Too bad. You were IRRESPONSIBLE! You should have read all the fine print before buying it.
Your local baker’s muffin has arsenic in it and you ate it and died? IRRESPONSIBLE. You should have known that the presence of arsenic is a possibility. You should have checked with the baker if they added it.
That’s a ridiculous approach.
Also, this isn’t new fangled technology. It exists and is widely deployed and there’s no evidence it increases failure by any meaningful amount.