I would have agreed with you on that not long ago as I thought that's how it operated, but the blog post does suggest that the internal studios don't have as much freedom to do their own thing as I believed. I guess a studio needs to have earned a lot of faith to be given carte blanche to spend Sony's money without Sony getting a say. I also wonder if there's a lot of regional difference, as the SCEE financiers are bound to be different people with different values to those running SCEJ and SCEA. A lot of positive comments I've heard about Sony this gen have been associated more with Phil Harrison. Looking at this list of Sony's 16 studios, I'm seeing a lot of one-or-two IP 'factories'. Guerilla just produce Killzone. PD just produce GT. Liverpool just produced Wipeout and Formula One. I can see three studios producing a lot of varied content - Studio Japan, Santa Monica, and Cambridge. (goes googling) Tell a lie, Santa Monica is a God of War franchise machine with support for other developers creating their broad library. Only Japan and Cambridge are producing multiple different games.
So it really does seem to me to be a case of Sony seeing their internal studios as producing staple AAA titles. GoW, GT, Infamous, Killzone, Motorstorm - whatever a studio enters into a generation with is what they typically will see it out with. That makes some sense. "You've made this great title and it's sold lots. We'd like to cash in on another iteration rather than risk a new franchise that might not be so well received." Then again, it could be the studio naturally wants to develop its ideas over the years. One obvious difference I see between Liverpool and other studios is that they stuck with the same franchises from PS2 to PS3. But then so did PD. I'd certainly like to know who's call that was. Given that we hear Liverpool were working on a new IP for next-gen, it sounds like they were trying to make a change and had been given the go ahead, but Sony had a change of heart. Perhaps it was too ambitious and Sony don't feel able to carry devs for too long now. I'm sure Team ICO's debacle has made Sony reevaluate more critically than perhaps their internal studios have been used to.
You are obviously being completely selective, ignoring my point, so I have nothing further to add.