Also pain and pleasure have been human experiences correlated since forever[1]. Just because the author has had a certain upbringing doesn't mean that she is the voice of the reason.
Even leaving neurochemical pathways aside, our culture is like that in many aspects. I mean even selflessness is the way many people understand being a good person, doing something good that feels bad is supposed to be better than doing something good that also feels good. I don't agree with that view, but it's pretty much ingrained with out western culture.