Linux is super fragmented (and generally has been historically).
If more people in Linux agreed to develop, use, and support the same distro–similarly to how most of us use the same kernel–then that distro would probably be better than Windows and more people would move to Linux.
The fact it can be configured so freely is one of the best things about Linux. A generic “one size fits all” solution would just end up being like Windows or MacOS.
That’s kind of exactly what it needs to go mainstream though.