I agree that it's crazy to act as though parental leave is anything like a vacation. I would prefer to sleep on my vacations. It's wildly unpopular among people who don't have kids, but I've come to think we should collectively want society to invest in kids, and that means parents as well. Raising kids is hard. It benefits society tremendously when it's done well.
The best ways seem to be things kids get directly, such as school lunches, better libraries, affordable child care, equipment at schools, etc. where parents don't need to be handed cash by the government.
But you're right, people get very up in arms about it (what about us?!). Society with an uneducated/un-cared for generation of kids is terrifying, though. I'm currently watching my oldest kids head into graduation with a cohort of kids who are clearly less educated than my graduating class was, and I'm dreading the knock-on effects. I feel for the kids too, but looking at this from a societal perspective: we're all going to pay the price for this. We should have invested up front.
In this case it's not possible to be certain yet, but the primary detriments to education among this cohort are probably covid lock-down and perhaps phones/social media? We got something wrong, regardless. They are less literate than previous cohorts have been for decades, apparently. Math scores are also much lower. Rates of plagiarism are so high that it's virtually impossible to address meaningfully.
All that is to say I think we should be doing a lot to ensure families and ultimately kids are able to thrive and do their best. Society ultimately profits from it, across demographics, for decades.