Chemistry sets packaged as consumer products are regulated, as are their constituent chemicals whether they're packaged for consumers or for industries. Meanwhile, parents and teenagers are more terrified of chemistry sets than those products actually deserve. As a result, there appear to be fewer incidents of chemistry set accidents than there were accidental ingestions of rare earth magnets. (It turns out the search term you're looking for here is [chemistry set poisoning]).
I feel like this kind of makes my case for me: Buckyballs was marketing a desk toy that turns out epidemiologically to be more dangerous to children than leaving a chemistry set unattended on a desk.
Just so we're clear: I think most parents are unreasonably afraid of chemistry sets. I agree with you on that. But --- bear with me here --- that's also a reason why we don't have to crack down on companies marketing chemistry sets.
I understand what you're saying. I just think that the benefit of over-protectiveness (no need for heavy-handed regulation to prevent some deaths) isn't enough to counteract the lost benefit from, for example widespread comfort with chemistry and chemicals. The level of risk-aversion is too high.
As an aside, I don't see much effective difference between a legal crackdown and one caused by fixing the social context.
You're saying they're being heavy-handed, but to be clear, all they are saying is that you can't market rare earth magnets as a "consumer product intended or marketed by the manufacturer primarily as a manipulative or construction desk toy for general entertainment, such as puzzle working, sculpture, mental stimulation, or stress relief". They're not banning magnets; they're banning one specific marketing of them.