The hypothesis is that the 'stack' is much taller. Back when all you needed was QBasic to "learn to code", "learning to code" meant reproducing other software you used on a daily basis.
Software is generally much more polished now, and it requires much more time and work to get it so polished (assuming it's at all complex).
I'm not saying I agree with this. But the situation is definitely different from 10 years ago by quite a bit.