On the other hand, there's a deep learning deficit that that generation will never recover from. That has costs too, and people trapped in a bad economic situation because of shitty schooling have reduced lifespans as well.
I agree that longterm closure of schools was a bad move and created many problems. However, I do think to be fair we need to look at some of the other issues at play regarding education. The system was barely working to begin with. It seems that countries with better school systems (or educational cultures), or just individual schools/districts here faired much better. The broken system can't play catchup if it was struggling to meet the basic education to begin with.
There's always a strong tension between the two points:
1) School closures were good, kids weren't harmed at all and it saved lives!
2) Schools provide the basis for future success and are critical to our social and economic well-being!
My stance is that, as mediocre as many public schools are, they provide a better environment for learning than home life for the majority of children. We should be moving toward making public schools great. (I'd be the first to agree that a broken system makes that a very difficult task.)
There's really no evidence public schools are a better learning environment than homeschooling, in fact there's evidence to the contrary.
Even when you include the extreme fringes of homeschooled children such as religious fundamentalists and unschooling, homeschooled students perform better on average.
This is probably because many-to-one learning is MUCH less effective than one-to-one learning, even with a massive difference in skill. Individualized learning is far better. Schools are the opposite of individualized.