Not necessarily true. A phone can be bent without signs of scuffs. A thin case that provides no (very little) structural integrity might keep scuffs at bay but not bends. A bent chassis won't necessarily immediately exhibit cracking in the screen.
I'm not playing the blame game. I don't know that the OP bent or even if it is bent. The reality is, particularly since its out of warranty, Apple doesn't really owe anyone anything in terms of manufacturers defects, especially if there is a possibility of end user abuse or misuse of the device.
Do I believe this particular model bends much easier then it should? Yeah, I actually do. I was pretty vocal about it in the months after the phone launched. My opinion is mostly irrelevant though. We are discussing Apple's grounds for denying free repair.