You're buying into the idea that multiple competing flavours of the operating system is bad. This 'fracturing' of the Unix market has lead to an extremely competitive and fast moving market.

Sure the vendors innovate to try to get the edge on the competition, but they can't stray too far from 'standard' Unix. Features that really take off are eventually adopted by all players and become part of the 'standard'.

The standards themselves are a combination of 'de-facto' standards and industry standards controlled by a standards body. In a competitive environment, you can expect industry associations to start setting 'Windows' standards with input from the various players.

Everybody does "Embrace and Extend". If the extension is bogus, it will generally die off. If the extension is useful, it will give the innovator a competitive advantage for a year or so. Microsoft's monopoly allows them to "Embrace, Extend, and Destroy" - basically they break their implementation of the standard at an appropriate time in order screw the other people who have adopted it. That's only possible as long as one party dominates the market.