The problem is that all the graphs that show children in school more do better academically show correlation, not causation. It definitely doesn't hold for all children, and it doesn't address the root causes.
I know several children with chronic conditions. Yes, they spend less time in education, and their lives are limited in a myriad of ways which mean they have less time studying (and also feeling well enough to do all the things other kids get to do). It's not the time in school which is the problem it's the health condition. And instead of helping and supporting those children to do the very best they can with the cards life has dealt them, schools are browbeating parents about attendance.
I am sure the most genetically robust children have lots of advantages in life. How lovely it must be to only rarely get ill and bounce back easily. I am sure this makes focusing on education much easier. But this isn't something we can magically think ourselves into.
Attendance policies in schools come very close to - if not actually being - disability discrimination, and in some cases risk chldren's safety (if the school is obsessed with attendance to the point of not sending children home when they need to).
The range of 'normal' (and that's before you get to chronically ill or disabled kids) in children is very wide in terms of days of sickness per year. As long as children recover within a normal time frame for each illness (usually about 2 weeks) the GP won't be worried. Why do the schools think they know better?
Yes, those who win the genetics lottery do better in almost every aspect of life - brains, health, fitness. Big surprise. It goes against all the purported school values to punch down on people for being ill a lot and that is the effect of these policies.
For children who have attendance problems not related to illness (though often it's related to anxiety, or SEND) then the school usually knows who these are, and they need time and support to make any difference, and maybe - even then - they won't get up to the mythical, plucked from the air figure of 97%. I know SO MANY parents who've resorted to homeschooling because they struggled with attendance and the school did nothing to practically improve the child's life, just kept on putting pressure on already struggling parents make both the parents and child's life a misery and ruining their wellbeing.
The best schools resist this push for attendance no matter what. But not all of them do.