I've heard that before and disagree that is a characteristic of a "real photographer". [*]
If the photographer looked at the scene and liked it enough to think it worthy of a photograph, what changed when the equipment got set up? It just sounds pretentious, whoever originally said it. I can just see Ansel driving through Hernandez, spotting the town glowing in the sunset, moon in background, scrambling out of his car, setting up the 4x5 on the roof, calculating the exposure in his head, then saying "naaah, forget it".
Of course, if he missed the precise lighting he wanted, I understand. But the original statement didn't qualify that.
[*] claiming what a "real photographer" would or would not do is yet another
No True Scotsman argument:
https://en.wikipedia.org/wiki/No_true_Scotsman