Generally, if someone tells you they can't do something, the reasonable reaction is to accept that at face value.
I think it's a bit rude to doubt people and ask for the real reason.
Sorry screaming but I disagree.
Hiss is most probably right to doubt that all of the people who say they 'can't' bf, can't do so for genuine physiological reasons (I believe the estimate is around only 5% of women can't physically bf for some reason?).
Finding out the real reason someone claims they can't bf is only a problem if it involves judginess and I really didn't get a sense of judginess from her post. In fact, not accepting things on face value can have positive results.
I, for example, 'couldn't' bf DD1 because after 24 hours my nipples were cracked and bleeding and I was in agony. I know now that it was down to poor latch and lack of support. It is only by exploring the reasons why women like me were unsuccessful in breastfeeding that the severe lack of support has been identified and is now being addressed.
I am (touch wood) now successfully bf'ing dd2, but that is only because of much better support.
Similarly it is important to identify those women, like yourself, that genuinely can't bf for physiological reasons so that research can be done and possible 'cures' found so that all women can have a genuine choice.
It is arguably rude to ask for more details from those who say they just didn't want to breastfeed, but finding out the reasons behind that decision is interesting just in terms of understanding human behaviour and thought processes.
The issue, particularly on MN, is when any one asks why a particular parenting, and in particular feeding, decision has been made, it is automatically assumed you are asking to judge rather than out of genuine interest / curiosity / desire to change things or help and people's automatic response is to get defensive or aggressive.