Psychological harm caused by forcing mask on young children is well documented. So forcing something on them that has no positive effect matters a lot.
Basically the only place masks are a good idea is where the captive audience can't be vaccinated, which happens to be schools.
That is something you have choose to believe.
Given quarantine policies for exposures the easiest way to keep kids in schools is to make sure the adults around them are vaccinated and that they take precautions before then.
My state effectively hit zero Covid deaths too a few months ago and that was through vaccination.