I'd love to know which computer from the 1980s was in hindsight the most future proof or capable. Not necessarily the most powerful but just kind of had the best throughput for its architecture or had the cleanest design. I think a lot of people would say the c64 or the IBM PC but it'd be hilarious if it was the sega master system or something
1985 saw both the Amiga and the 80386 PC, which with DesqView had fully preemptive multitasking, but wasn't a proprietary platform. The Amiga admittedly had superior graphics - but the PC was more "future proof" because of that openness.
Just because it wasn't visible to you doesn't mean it wasn't heavily used. I worked for Quarterdeck, supporting DesqView, for years. It was used in industrial process and business backend until amusingly recently. It was the Jack-in-the-Box order system for years past when it should have been obsolete, because it worked and was super-reliable. It was used in a ton of point-of-sale software as well. And it was used because the PC had an extensible bus you could add all sorts of hardware to - that never materialized for the Amiga.
I wouldn't be surprised if there aren't still industrial processes that run under it today, despite being horribly outdated, because it just worked, and replacing custom industrial hardware is expensive.
@Biggles @upmultimedia absolutely nobody adopted or supported "desqview." The point isnt that the amiga was the first multitasking os ever - it obviously was not - but rather it was the first widely supported one.