Yeah, I think people are underestimating how good and competitive the Linux desktop was in the past. Around ~2000 there was a lot of excitement around the Linux desktop, the Linux desktop was pretty mature, especially compared to the tire fire that Windows 9x was at the time (that changed when the NT branch moved to the consumer with XP). There were very user-friendly installers like Caldera OpenLinux (best feature was that you could play Tetris during the install) and Corel Linux. Also a lot of large vendors were making Linux desktop apps, e.g. Corel Wordperfect and Borland Kylix (which was Delphi for Linux). Heck, even Microsoft Office ran almost perfectly with CrossOver.

But yeah, then there was the constant forking, preferring rebooting development over iterative improvement (e.g. GNOME 2 -> 3 was really a hard cut for a lot of people, resulting in forks that exist till this day), hostility towards closed-source applications (you can hate them as much as you want, but people are not abandoning Photoshop/Illustrator for GIMP/Inkscape on a whim), etc.

Hopefully something changes with all the government-driven sovereignty desktops that are popping up, the resulting influx of money, and KDE EV et al. becoming very mature organizations.

By such measure, GNU/Linux phones are already quite good. I use Librem 5 with Phosh as a daily driver, and it is really just fine. Except the battery life, app compatibility and smoothness of the UI.