EDIT: source - been doing Linux for corporates, big and small since 1999.
The main problem with Linux adoption isn't choice - every beginner can easily find out a reasonable distro for starting out - but motivation to do the switch in the first place. Almost nobody is used to Linux and doesn't know a reason to try it. Even limiting the choice to one single distro isn't going to change that.
People's computers are like their cars we like to customize and mod them because it's cool and remember, you own it so it gives a sense of pride.
There was a glimmer of hope at the start when the focus was on just getting the full free software stack working. But then it went back to making near-exact copies of the most trivial parts of it.
Why nobody ever copies the hard parts?
- Debian and *buntu - Red Hat - Fedora - Suse
All of them use systemd. All use X11 or wayland. All package gnome. All DEs, WMs etc. are available on all these distros.
Smaller distros can reuse whatever is available for that distros, see for example chrome or skype.
But regardless, I agree, fragmentation isn't really a problem. It would be very rare indeed for some software to only work on some distro but not another. And if this was the case, you could probably change it with enough work (swap out libc or whatever).
https://aur.archlinux.org/cgit/aur.git/tree/PKGBUILD?h=googl...
Google only packages chrome as .deb and .rpm, but you can still get it on other distros anyways.
Here's two examples of how distros patching software has been helpful for me.
1) SquirrelMail (abandoned) patched to work with PHP 7.3 thanks to FreeBSD contribs
2) Abiword patch builds in the AUR that fix a broken default install.
I'd rather see that useful changes are merged upstream, or projects are forked. If this had happened, you wouldn't even need to patch, and this would save an enormous amount of manpower that is wasted on trivialities.