But once again, until the actual product comes out, it doesn't make sense for people to buy a console when the only thing that interests them is said future title. But sure, let's excuse the PS3 purchases. At this point, I haven't seen anyone say they bought a PS4 for The Last Guardian, so I don't know whether anyone really did that. With the PS3? Sure.
I wouldn't say people bought both consoles solely for TLG, of course. I bought the PS4 on the promise that the next Uncharted was going to be developed for it sooner or later, but I got it for most first party offerings as well.
I just found it kinda funny (or sad?) that those who got the PS3 and PS4 mainly for TLG are still waiting for a game that's almost certainly cancelled.