This wasn't a "lie to children" - that's a simplification. This was like explaining the Pythagorean theorem by introducing imaginary numbers.
Almost nobody ever uses hex to represent IP addresses ever. There is no reason to bring up hex. It complicates things rather than simplifies.
And to say "[t]hey are actually hex numbers from 0 to FF" is just misleading to the point of wrong. Numbers are not "hex" or "base 10" or "binary". They're numbers. We only represent them as hex or base10. They aren't "different numbers".
And in this case we almost always use base10. SO WHY ARE WE TALKING ABOUT HEX?

