Do you have a sense of whether that's harmful at the margin (a small reduction from typical produces better results), harmful in total (our results are presently worse than if there was no homework at those ages), or harmful in any quantity?
> harmful in total (our results are presently worse than if there was no homework at those ages)
Most studies compare schools / classes assigning no homework to various "normal" levels of homework, so they imply that our results are presently worse than if there was no homework.
I do assign homework to middle school students. But I don't do it often, and it's typically of the form "think about an idea on the topic of _____ we can discuss" or "do the first couple items of this lab worksheet so that we can use our time in the classroom more efficiently tomorrow." I enforce its completion with social pressure, not the gradebook. "Dude, you were supposed to do the first couple questions on the lab worksheet!"
I have a feeling that there is better homework we could assign that would be useful. But we don't have a lot of evidence of what that would be. Proponents of flipped classrooms think that is the path forward, but the research quality is very dubious in primary education.