The author also linked a more recent review of Wayland at the top, which could be more interesting.

(I'm too incompetent to talk about anything technical but just to point it out)

The author talked about cursor latency being worse with Wayland, and claimed that it was likely a consequence of the major architectural differences between X11 and Wayland. Is this an inherent drawback of Wayland, or is it just something that's true for one implementation, e.g. GNOME?

It's a implementation issue(or a driver), Wayland don't dictate the mouse latency, and compositors are free todo whatever they want with it

I figured. I'm not sure if the author meant that it was an inherent drawback, but it does seem like he still has a bit of lingering bias towards X11 in his reassessment article.