The benefits and detriments the children get by working are not equal to those they could get if they were able to get an education and have free time to play, instead.
"This is beneficial enough that some people choose it" and "this is a genuine good thing for those people, compared to the other options" are not equivalent.
"This is beneficial enough that some people choose it" and "this is a genuine good thing for those people, compared to the other options" are not equivalent.