>"Young people know all about computers" was never true either.

That's true, but only because not all young people owned or used computers. I was born in the mid 70s and got my first computer as a young child. Back then you had to "know all about computers" to use the computer and get it to function. These days, every kid grows up surrounded by computers, with a computer in their pocket, and very few have even an inkling of how they work.

Thus "young people who use computers know all about computers" used to be a true statement, but no longer is.