I think, yes, you can marry a man who is impotent or a woman who have no womb and that would happen when you are seeking a true companionship and nothing else ( like physical relationship, children or any other purpose).
I have seen many old aged people marry because they are alone and they need someone who can just live with them like a good friend and provide some meaning to the life that they were living otherwise.
There would be other cases, where people who are medically challenged, or are not able to live a normal life, would also try to opt for similar partners, or someone who can fill the gap in their life.
