It's supposed to be making a case against jQuery if you're pulling in the whole library just to do this one thing.
I've always read the site as "here's how to do it in native JS, yes it's uglier, but if you only need this, you can skip pulling in another dependency."
Over-engineering websites has been around forever. That's partially why jQuery is modular, letting you pick what you need.This covers the 'use jquery for just this one thing' crowd. And if they're lazy, well, they can hang their heads in shame because they have added an entire 83 KB to the page's initial load time. /s
(unless the browser has a CDN cache stored, in which case it wouldn't impact load time at all)