Web development-centric websites often seem to totally ignore the need to provide a usable mobile experience. It’s maddeningly weird.

It's not unsurprising. Web development happens practically exclusively on desktop/laptops.

Maybe I'm a small ignorable minority but almost all my library skimming is done on a phone. I explore new technologies when rocking babies to bed or dozing off myself.

And yet, desktop browsers have no more need of hijacking the browser's scrolling behaviour than any other browser.

And leave scroll bar rendering to the browser or OS vendors!?

Think of the pixels!

/s

Seriously though I believe it's often done to make infinite scrolling and scroll-transitions more visually pleasant. (Not that I agree with the sentiment, but if visuals are more important than anything else...)

And yet many of the sites I build have majority mobile traffic. It's borderline incompetent to ignore the mobile ux these days.

And the clicking/drawing/dragging interactive demos ignore touch input, but also block touch scrolling.