Part of why people are upsetis because they think this is a much more recent example of the thing they dislike than expected.
It's disingenuous to pretend it's only the practice not the context which influences people.
I think the best argument is that three year olds would make extremely ineffective chimney sweeps. I don’t know if you’ve met any recently? They would require more effort in supervision than they save by way of their labor. Much more.