A good question Knickerful, and probably not one I can answer satisfactorily.
I read the Feminist threads on a regular basis, and often try to measure up the opinions on these forums (or fora) against my own behavior. I do not always come out smelling of roses
So when I read this one about consent, I did wonder if it was as straightforward as the very well written article implied.
This in turn made me reflect upon some of my experiences, the one I related has remained with me a long time, as well as a few others that I have not related.
I hope that explains 'why', to some extent.