"Ballmer made several missteps:"

Growing an already massive company company by 3x in revenue is the important thing, which is the 'bottom line' in which missteps have to be contextualized.

Any company in tech is going to make mistakes, this should be happening, so listing them off doesn't so much help - what matters is how all of this works out in the mix.

I worked in mobile during that time, it was vicious. Surely MS could have done better, but I view it more as lost opportunity than failure.

Remember that 80% of acquisitions fail. Google spent $3B on Nest. Apple spent $3 Billion on Beats, it remains to be seen if they'll make that up in profit.