I was an 'average' child, very much so, but I was an average child in the70s/ 80s, when I would say it genuinely didn't matter as much. We average masses were 'factory fodder'. We could still expect to get a job that paid enough to pay the rent/get a mortgage. I have spent my life doing average/low paid jobs, but was able to get a mortgage with my DH at a young age and do fine by putting the hours in.
That just isn't an option now. Whilst every child might have a talent, though it's lovely if it's being 'kind and caring', kind and caring won't get you a job that pays the bills these days. I hate that that is true, but it is.
It matters now more than ever. With more and more jobs being automated, AI on the rise, kids today face an uncertain future. There's no reasonable adjustment for just not being very good at stuff. And the work so many of us 'not very good at stuff' kids used to end up doing is either disappearing or just doesn't pay enough to live on.
It's all very well people talking about 'trades', but trades that pay aren't unskilled. Not every average academic child is going to be God's gift to plumbing. Lord knows I had zero practical ability.
If your child is, like me, genuinely just average to below average at anything that has a remote chance of earning them a wage, unless UBI comes in they'll be working ridiculous hours trying to scrape by. So, I kind of don't blame parents for wanting to believe that isn't their child. It's awful to want so much from a child as early as Primary school, but I think many parents realise just how tough it really is going to be for 'average' children. People want it to be the case that a metaphorical kick up the backside/tutoring/pushing the school to recognise their child's 'potential' will solve the problem, will reveal the talent that will save their child from a tough existence on the bottom of the pile, fighting for what's left of the unskilled jobs.