Argh.
May I be candid? This is like hearing what Christianity and Islam have to say about what the One True Religion is. Or hearing fans argue which Final Fantasy is the real Final Fantasy and which is more or less or not.
I will never understand why some people take edition-love or system-love so seriously, but the way I see it, we should define D&D the way the normal-Joe would define it and keep all the veiled edition-championing, if any, in check: which is to say I think Pathfinder is Pathfinder and all editions of D&D is D&D--no loaded meaning or subtext needed, here, now, or ever.
D&D is not a taste, or a category of gaming (card games, board games), or a school of thought; it is a particular rule set for a tabletop role-playing. I understand that some people use the term 'D&D' synonymously with 'TRPG' but they really shouldn't. We don't say we're going to play basketball when we mean we're going to play sports, even if basketball were the most popular type of sport among sport fans.
Is 4E less D&D than Pathfinder? I, for one, could care less because honestly, we are all part of this one big happy family of nerds and we really need to stop attacking each other for liking a certain rule set over another.
A. I like dogs.
B. You like cats.
C. We both just love our pets.
D. Dogs are real pets. Cats are fickle.
E. Cats are real pets. Dogs are just hardwired to obey and follow like a moron.
Let's all focus on C!