Let's look at colorblindness. This is a recessive trait linked to the X chromosome. It's more prevalent in men because we only have one X chromosome so for men, it expresses itself as a dominant trait.
If every man with the flawed X (outward signs of colorblindness) didn't reproduce, then there would never be another female who was colorblind again. Can't happen unless the father is colorblind and the mother is either colorblind or a carrier of the flawed gene.
So lets assume all men with the flawed X stop reproducing. Let's imagine a hypothetical where they are all aborted in utero.
Thus, there would never be any chance of expressing the gene ever again.
But the gene would still pass on.
The mother would have a 50% chance of passing it on to her daughters.
It would continue on in the females who will never, ever express the trait for eternity. This is how it passed on to me. My grandmother is th ecarrier, who passed it on to my mother who passed it on to me. She may have passed it to my sister, who in turn might have passed it to her own daughter.
The fact that the gene is extant means it will always end up resurfacing.