KDE actually looks halfway decent though. Unity (if that's what Ubuntu's still calling it's UI?), though, most definitely has "hobby project" written all over it. I tried Ubuntu for the first time recently and all kept hitting little catches and speedbumps - but they weren't "oh, that isn't implemented" or "oh, this doesn't work that way", they were all bugs. The alt-tab subwindow thumbnailer lets you select multiple application windows at once. The screen locking system not only gets extremely confused by fullscreen windows, once said fullscreen apps exit the system belatedly picks that exact moment to go to sleep. Notification toasts cover the type-to-search box, which is fun when said toasts decide to get stuck on the screen. The hotkey system eats ctrl+alt+(left|right) even though the system is configured to use vertically-aligned desktops, so I can't switch between desktops in my openbox VNC session unless it's fullscreen. The system doesn't feel holistically tested. I'm sure there is actual testing done, but it feels like <10% (<5%?) of what Windows/Office/etc gets.

Sure, perhaps things will be in a different place in 5 years. (Especially if The Dispatchers Of Wisdom™ don't decide to give up and start again with a new UI and applications. Cynically not giving the current effort a high chance of surviving...)

OK, my point/question: I think one of the prerequisites for hobby projects to make it big is playing in a space that's largely uninteresting or undiscovered to the majority of people that will notice (and understand, and feel threatened by, and respond to) the new thing, before it has reached critical mass. Perceived risk being somewhat irrational and all that.

KDE and Unity feel like hobby projects because "desktop Linux" is forever the thing that never really existed, and the only people who pursue the idea are people that don't get that. But their work gives enterprises some free source code with APIs that let them make application windows with buttons in them! Nice! But there's no point for those enterprises to contribute functionality back to the UI engines, because that doesn't further the enterprises' application-specific focuses.

Web browsers definitely aren't an undiscovered thing by this point. I'm sure more people than might reasonably be expected probably check out where NetSurf is up to every 6-12 months or so, for example. (I don't mean hobby project users here, I mean would-be commercial users with adequate domain savvy to be aware of the entire ecosystem. Total theorization on my part but I do wonder if I'm right.)

"A new kind of web browser" is a fun idea, but impractical in practice as it's preeeety much the polar opposite of an unknown idea now. A new web browser would be subject to an atlas-holding-up-the-entire-world level of passive and active social scrutiny if it looked like it was taking itself seriously. (Servo is kind of a good reference example there. It wouldn't survive if it didn't have Firefox and the indefatigable Rust team behind it; and even as it is things are still struggling).

By the way, serious question - what does source-level access to Chrome mean, at the end of the day, for the vast majority of internet users? The only real quantitative (not qualitative) answer I have are the small high-reward collection of bug bounties that have been rewarded over the years to external contributors. The fact that you can build Chromium and ship it [as part of Linux distributions] does feel a bit like an implementation detail that fulfills Chrome's goal as a technology moat (and competitor to Firefox).