That's true, but it means a limited, even non-existent corporate wide strategy beyond 'make profit'. If leveraging their assets can produce more competitive products and significantly grow their market share and profits beyond selling to rivals, that'd be a Good Thing. This was many of ours expectations come PS3 - that Sony would leverage it's divisions to provide an all-in-one solution. Movies cooperating with gaming to provide a steaming service, a universal login across Sony Entertainment, selling Music via a rival to iTunes, mobile phones tapped in to this Sony Network streaming Sony media, etc. Sony's inability to capitalise on their position is a significant part of why they're in this mess.For example, Sony CMOS sensors are in high demand currently. There's a guaranteed market for them that is very profitable.
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In short, in that example. It's obviously in the best interest of the phone division to get the sensors at cost or at a discount. It not in the best interest of the devices division and may not be in the best interest of the Sony Corporation as a whole with regards to profit generation.
The present move is probably good for a conservative approach to their future, but it means a Sony far less than it could have and should have been. I suppose there's no going back though, and that opportunity around 2000-2005 will never come again.