Using links or buttons would suck for a lot of use cases. Imagine what it would work like on your phone if you couldn't scroll through Twitter, but had to touch buttons.
Funny that you use Twitter as an example because infinity scrolling on
Twitter is the reason the side is so unusable. Whenever you click an
image/link or try to zoom in/out, you take the risk to lose your current
scroll position.
? I have a touchscreen
Honestly scrolling on mobile gets me halfway to a repetitive stress injury, I’ll take a next button anyday