Mind that continuous scrolling was a function of the scroll buttons (arrow buttons), which were axed in favor of visual simplicity. You just kept them pressed for continuous scrolling. On macOS, absolute scrolling is still Option-clicking on the scroll track, while simple clicking is paging. (I don't know, if this is still a thing on other GUIs, though, but I hope it is.) The size of the scroll thumb gives an indication for what a screen size is in relation to the document and what amount of movement is required when dragging it. (This was a noteworthy contribution by Windows, while it was also arguably bad about minimum sizes.)
Most of this had been addressed by the original design. Loading additional content will be always a problem, though, since it necessarily breaks any spacial relations already established. (But this is really a problem of infinite-scroll designs, which simply do not match the established UI controls, without caring to provide any suitable replacement or work around or even suggesting a metaphor for this. Which, in fairness, is to be expected for what is essentially a marketing instrument.) Scroll wheels and trackpad gestures will be arguably superior for continuous scrolling for most users, but cover continuous scrolling only and none of the other options provided by the scrollbar (especially, a fully implemented one.) – There's much to do in order to catch up.
Most of this had been addressed by the original design. Loading additional content will be always a problem, though, since it necessarily breaks any spacial relations already established. (But this is really a problem of infinite-scroll designs, which simply do not match the established UI controls, without caring to provide any suitable replacement or work around or even suggesting a metaphor for this. Which, in fairness, is to be expected for what is essentially a marketing instrument.) Scroll wheels and trackpad gestures will be arguably superior for continuous scrolling for most users, but cover continuous scrolling only and none of the other options provided by the scrollbar (especially, a fully implemented one.) – There's much to do in order to catch up.