Unix had it different with there being no core experience in the first place -- X11 being a glorified terminal multiplexer plus xeyes. Whether it was the commercial Unices with OpenLook/NeWS vs Motif/CDE or later Linux with Qt vs Gtk. Not that there wasn't a chance -- at one time Motif won over the commercial sector and if it would've been available with the same license as Xlib/Xt, GTK would've never been developed.
But that seems to be a thing of the past. These days the web forced us to give up all platform-specific UI expectations -- heck, any expectations of having a proper UI in the first place. And thus applications are all over the place, Electron being just one particularly heinous culprit. Material UI on the desktop. Plenty of applications starting up web-based interfaces in the browser.
On the one hand, as you say, this doesn't make the particular desktop matter anymore, it's more a vehicle of getting your wifi driver to work properly and load the browser. So one could use Linux or even Haiku without any big losses. On the other hand, if everything's pastel-colored oatmeal, there's no big benefit from a neat, unified, C++ desktop experience that BeOS was aiming for.
If you want a vision of the future, imagine HTML stomping on your face -- forever.
