That's just preposterous. Linux user friendliness has not been slow or fragmented, it has come really far just in the last five years. Windows on the other hand has gotten relatively worse since the 'high' periods of early NT kernel OSes.
> The most important dimensions for an operating system are usability and compatibility.
Incorrect. It is only "one" of the important dimensions, but to call it "the most" important one is at -at the very least- misguided and absurd.
> The most important dimensions for an operating system are usability and compatibility. Average users are like this while hard core masochist programmers are willing to spend years decoding an interface
Your inability to use many of the user friendly distros available (like Mint or Elementary) cannot be generalized to the wider public.
Do some research.