GEM on the PC was... ick... compared to on the Atari ST.

But the problem with GEM on the Atari ST is that in order to cram it into the 192KB ROM they ripped out some goodies like proportional font support which ended up being in an add-on called "GDOS" which was buggy, used up RAM, and most people didn't have it (it came with things like DTP software etc).

In general this was always the problem with the ST. The Tramiels shipped it early and cheap and awesome and I loved mine ... but then didn't pay enough attention to software updates until it was too late and the world had moved on. Jack Tramiel never really understood the value of a good software platform IMHO.

In the early 90s they seemed to learn the error of their ways, hired some talent, and released full multitasking re-entrant versions of TOS/GEM ... but too late.

GEM's architecture itself underneath actually was clearly built for a mulitasking architecture complete with message passing between applications (via AES application msg send / mailboxes) etc. It just came down to failure to iterate.

Also the article mentions DR "hiring some people from Xerox" but in fact fails to note that the actual original architect and author of GEM itself was hired from Xerox (Lee Lorenzen). He joined up with DR because he tried to pitch Xerox on porting their Star office concepts down to PC-class hardware and they didn't go for it. His pitch video can actually be seen here:

https://www.youtube.com/watch?v=EMBGRZftS30

Lorzenen later left DR and created Ventura Publisher.