The variety of distributions in the Linux ecosystem is a strength, not a weakness.
No one is making you pick up a shovel to build alongside them; instead you choose to rest on your laurels and complain about other peoples' hard work and dedication to providing people with choices.
The fact that less than 5% of desktop users and 0% of mobile users [0] use Linux speaks for itself. All the effort that went into creating distros could have been focused on few high-quality ones.
[0]: Android uses the Linux kernel which is almost the same across distros, but isn't per se a Linux OS. I'm talking about real Linux running on a mobile phone.
This argument makes no sense considering the diversity of tastes and desires in the community. It’s incredibly difficult to put more people to work together and achieve superior results, especially if it’s something decentralized and voluntary. You can pretty well end up with more chaos and internal conflicts instead.
Why are you so hellbent on dictating how volunteers spend their time?
Have you ever considered that these people are satisfied with their interests and truly could not care less about your opinion? Or that your opinion is just that-- yours? Not some absolute truth?
Anyway, it's beside the point, as there are multiple high quality Linux distributions to choose from, thanks to a large de-duplication of efforts through libraries.
No one is making you pick up a shovel to build alongside them; instead you choose to rest on your laurels and complain about other peoples' hard work and dedication to providing people with choices.