I started noticing some sites were hijacking scroll despite having them blocked by NoScript, however the above config change fixed that instantly. Turns out scroll can be hijacked by CSS now, not just JavaScript. Progress!
Given how much thought he puts into user experience in his projects, that's really weird. I have to scroll with click and drag and sort of "throw" the page upward as if I'm using a touchscreen.
To hazard a guess, the testing environment was a Mac with trackpad scrolling. Each scrolling step on that would be small enough that "teleport to next scroll position" looks smooth, and breaking the built-in smooth scrolling wouldn't be noticeable.
I do wish people would stop trying to reimplement scrolling and just let the OS/browser do it...
FWIW I'm in Chrome 54 on Windows 7.
It's kind of when fashion designers wears an ill fitting t-shirt and jeans I guess.