I think that MacOS could be sold much better than it is today when everyone would just get some information about other operating systems.
Unfortunately the "This superior operating system won't run the 90% of software in existence"-tidbit would be the dealbreaker to the vast majority of the people.
Like it or not, Windows (with all it flaws) still has a critical mass when it comes to market share, and that alone makes all other options marginal, regardless of their actual technical merits.
It's a bit of a catch-22...