[inimino]

It's not hard to understand, it's just totally irrelevant. Let's say one percent of the people taking a temporary contraceptive (rather than just having a vasectomy) happen to also not care if they are made permanently infertile. Meanwhile, another one percent get this side effect. These aren't going to be the same one percent.

The fact that there may be men in the first group is totally irrelevant to the experience of the second group.