To be honest as a user, I'm glad they made this change, even though as a developer it might be a pain in the ass for a day or 2. Scrolling on the mobile web sucked for a long time. Yes, updating the default broke many things, but the scope of that breakage was fairly limited in the grand scheme of things (like the author said, sliders, maps, touch-and-draggable things like lists are the biggest impacted, stuff like "…
How is it good for the user if it breaks the website?
Yes, it breaks some websites, and for those users in that moment things might be worse, but it is making the web better for significantly more people, and even the users affected aren't really "impacted" by it in most cases (generally only seeing "sticky" headers warp around while scrolling outside of a few specific types of applications).