I don't doubt that's why you play it. But, with the huge amount of material that was already out for 3.5, did you really need to buy everything Paizo put out for Pathfinder?
It is actually pretty amazing how far from true this is.
It is quite easy to use 3E stuff. But people tend to not do so.
Remember that 3.5 was a major starting point of the D20 crash. Both 3PPs and stores had a ton of 3.0 stuff that players suddenly would not buy. It was very easy to use, with little (often zero) changes. But people wouldn't do it.
And the same thing happened with 3.5 to Pathfinder.
But, 'validation' aside, you must agree that the point of Pathfinder was to continue 3.5? I mean, it had "3.5 is back" right on the cover. I can't imagine that over a year of vicious edition warring, and a long participatory playtest, capped by that sort of image didn't build some esprit de corps.
It was "3.5 Thrives" (another one of those points that 4E fans scoffed over at the time and now cling to)
As to "esprit de corps", if you take away the narcissism you will realize this is silly. It was not about Tony. It was not about 4E fans. It was not about 4E.
Those people stood in line at Gencon because they were thrilled to have a game they wanted to play.
They were not playing 4E.
They were not playing GURPS.
They were not playing Heroes.
There were hundreds of game they were not playing.
Love of PF was not about sticking it to a game they didn't like, it was about a game system they loved being actively supported.
Edition waring has NOTHING to do with that.
the playtest and build-up of community did, sure. But these factors again have ZERO to do with 4E.
It was not about you or your game of choice.
the love of 3.5 / PF was about people really liking the system. period.
Take out the narcissism. It ain't got nothing to do with you.