I worked on the OS for the Atari ST. It sure wasn't ahead of its time. We looked at the Mac and felt jealous; that was some real engineering, while we had a bunch of crap from Digital Research (and a lot of it was unadulterated junk).

I never used things like MiNT, but those weren't supported by Atari anyway.

Atari just didn't have the resources to sink into an OS that could compete. They knew how to make cheap hardware, but after a while the PC ate their lunch. Nobody wanted to do biz with the Tramiels, so games were pretty much off the table.