surely some abuse of the drug could lead to adverse reactions?

are they just arguing for specific doses to not have negative effects? (that would be true of a lot of things we consider harmful)

Acetaminophen and dementia correlation:

https://pmc.ncbi.nlm.nih.gov/articles/PMC2877629/

https://www.sciencedirect.com/science/article/abs/pii/S01638...

Note that it's also hard on the liver. A lot fatalities due to taking after hangovers, etc: https://www.medicalnewstoday.com/articles/322813 So if you insist, maybe take some NAC.

But apparently, Ibuprofen helps counter the dementia risk:

https://www.aan.com/PressRoom/home/PressRelease/624

I am not not asserting any clever marketing here. I am merely citing public information. Noting all the above, I am confident it's perfectly safe for children and fetuses, and if posing any risk at all, applies strictly to full grown adults. No doubts about child safety have been expressed here.