how many developers they hire.
Aside from technological acceleration; the level of interoperability, modularity and portability of open projects is simply inconceivable to proprietary houses. It is for this reason that the Apples, Microsofts and Oracles of the world are already beyond revival. If in the depths of the information era they have still not accepted the advantages and honestly, the necessity of open standards then they simply cannot be trusted with information systems that need to be forward conscious and ever adaptable.
MacOS and Windows are competing platforms and the success of one damages the other. Ubuntu and Linux Mint on the other hand, are technologically complimentary. They still compete with each other for market share but progress stemming from either platform benefits both. The popularity of Android is making Ubuntu's entry into the mobile market far smoother. Instead of reinventing the wheel, Ubuntu developers can spend more time on building distinguishable features which will ultimately benefit Android as well.
The interoperability advantages of open source go beyond simple code and feature sharing however, whole platforms can be completely merged relatively easily and without the bureaucracy of consent or the encomberance of royalties. This is exactly how Ubuntu for Android was born. An established mobile platform merged with an established desktop platform to produce a 'best of both worlds' scenario that benefits competitor and consumer alike.
Democratically accepted standards coupled with the acceleration of millions of enthusiastic developers makes open source an unstoppable force. It's progress is certainly being slowed but it can't be beaten.