On a desktop or laptop computer, most trackpads have an immediate response curve. I am using one now, an Apple Wireless Trackpad. A very large amount of engineering effort over decades of time and millions of lifetime hours went into making it behave that way over a common wireless medium. I scroll a little bit, it scrolls a little bit, immediately, I scroll a lot, it scrolls a lot, immediately, and if I flick my finger from the bottom to the top and let go, it behaves as if I swiped a page of paper on my desk in the same fashion, with inertia taking over, proportional to how fast I flicked.
There is therefore an intrinsic physical link between the actions of my fingers, and the motion on the web page. My finger moves, and an immediate, proportional response is observed. This is an utterly base level of how most humans interact with the world. It is why using a mouse or trackpad came quite easy to many people (and why some can flick a mouse in a shooter, turn a precise 274.9 degrees, move up 14.2 degrees, and click on the head of an enemy player in fractions of a second with pinpoint accuracy). It is also why even a toddler can use a touchscreen; direct manipulation is inherently understandable to even a baby.
When I am turning in a screw by hand with a screwdriver, the feeling of the screws threads through the handle into my fingers, the immediate force feedback, the observable, feelable progress of the screw in or out of its screwhole, forms this same interface. Where human and tool meet, latency and unexpected behavior, especially if divorced from the input force, are undesirable qualities of a tool.
Scroll jacking is to a trackpad or a fine scroll wheel as turning a screwdriver handle by twisting a bungee cord is to using a screwdriver. It unhooks the immediate, direct feedback from the motion of my hand; its jarring, unpleasant, frustrating. On this page, I immediately put two fingers on the trackpad and moved them less than a centimeter, and didnt let go, and the entire screen cycled its view, as if I pressed a button "move to next item". Except I didn't (and why would I want that in the first place???), I just moved my fingers less than a centimeter. Nothing in the real world moves like that except for things less than a centimeter away from falling out of balance. And it feels the same. Precarious. A common human reaction to things moving out of proportion to our body is nausea!
I think a better question is, can you give an example of "why/how" this solves any actual problem someone would have had scrolling this website had it not used scroll snapping? Would the top comment have been "Boy I wish this site had used scroll snapping, it would have been more well done and enjoyable that way"?