Man, imagine that your console is in the hands of the chip makers who are making the competition's consoles.
*In a mock interview with IBM and ATi*
"We think that our chip for the new PlayStation will lead the world in interactive entertainment"
*MS glares at them*
"erm, sorry, the next Xbox"
*Nintendo glares*
"erm, sorry, the next Gamecube."
How can they say that with (insert company here) they are creating a superior chip that will blow away the competition, then turn around and say the same thing about the other companies?
There are other issues to be dealt with when ONE company is responsible for the development of your and your competitor's main product. It can lead to secret deals, sabotage, and bribes of a worldwide scale.
And since MS are the richest company of the three, they should be the one to watch. But then we should keep a critical eye on Sony and Nintendo too.