> fragmentation is the biggest thing holding back desktop Linux
I'm not convinced.
The main thing holding back desktop Linux is buggy upstream software not working, which usuall affect all distros. LibreOffice Writer didn't have a rastered ruler for 10 years, no quality GPU driver for some AMD card, some KDE app segfaults, some Python app has a value unexpectedly being None, a kernel minor version update just completely broke the version of VirtualBox on Ubuntu 22.04 LTS -- those were and often still are daily problems that no amount of distro hopping or fragmentation consolidation will fix.
The "large" distributions justify their existence by differing in key aspects that cannot be consolidated:
* Corporate vs community, e.g. RedHat/SuSE/Ubuntu vs. Debian
* Fundamental concepts, e.g. NixOS/Guix vs. everything else
* Up-to-date-ness, e.g. Arch vs. Debian
There are some aspects of fragmentation that _could_ be consolidated by better software and more configurability, e.g.
* Source vs. binary, e.g. NixOS provides both
* Choice of libc, e.g. NixOS ships glibc by default but you can easily get much software with musl, and it's technically possible (but needs more community power) to provide a whole system running musl with a single line of config for the end user
* GUI vs CLI configuration
For the small distros, they are niche enough that them merging with another distro doesn't have a huge consolidation effect overall. For example, I do not see how Void Linux and Alpine Linux merging would significantly improve the life of the mass of Ubuntu users, or signficiantly advance "Linux on the desktop".
It's true that there's some amount of duplicate work occurring, but much of that is often easily re-used across distros. For example, if in NixOS something doesn't work with the newest version of musl, one would usually check if Alpine already solved that and if yes, swiftly copy the approach. The main work is for the _first_ one to figure it out, and that work is necessary even if there was only 1 distro.
Reducing distribution fragmentation isn't what makes "Linux on the desktop" happen.
Fixing broken software, making good desktop environments, creating Wine or Proton or Pipewire or cross-platform software (LibreOffice, all browsers, Electron), does.