YABU. Good health is not a "gift" that is "bestowed" upon someone. It's a combination of lifestyle choices and luck. It's about playing the percentage game - a, b, and c increase your changes of enjoying good health, x, y and z reduce your chances.
With the attendance certificates, yes they are nonsense and have no value in the long term, but anything that encourages some children to come into school when they otherwise might have felt less inclined is a good thing. Fear of losing a perfect attendance record is exactly the sort of thought process that we should be encouraging in our children.
When they get to adulthood, they will find that employers are generally not that sympathetic to people with poor attendance. You can argue over the rights and wrongs of this, but the fact is that poor attendance at work affects the whole team and is therefore viewed as a bad thing - even if the reasons for the poor attendance are perfectly reasonable.
Employers can have bullshit official policies that "prove" how caring they are, but the reality is usually very different. Why do you think so few companies pay sick leave? In a common-sense world, if Mr Black is sick, a company should positively want him to stay away so that he doesn't infect Ms Whyte, Mrs Green or Mr Brown. But companies generally only pay statutory sick leave, because they expect the sick employee to make every effort to come in.
A child who has the "come in at all costs" culture instilled into their mindset at an early age will have an advantage over their less-committed peers when they enter the world of employment. Employers need consistency because an employee who is consistently at work and works to a consistent standard is a known quantity - they can be relied on. In most roles, aside perhaps from particularly creative ones, a consistently-average employee is valued above one who has moments of brilliance but cannot be relied on to be there when you really need them.
So yes, it's a good idea that schools try to cultivate this attitude, regardless of how worthless the attendance certificate is in itself.