Somehow the Atari ST is panned because it lacked preemptive multitasking (I'm not sure if this is true). They didn't mention any of the other GUIs that unix was working with - X11 already existed back then, and several unix vendors had their own windowing system that was arguably better (at least their marketing said so - I never used any). Of course Unix systems would have been much more expensive.
Let's not forget this was also the era of Atari ST and the birth of ARM with the incredible Acorn Archimedes arriving just a couple of years later.