Well, not everyone says it's best. My RE recommends using a couple drops of mineral oil on dh over using preseed. Many women have become pg using it, so if that's what you want to do, then go for it. It is probably better than using KY.
Yep. I thought I was doing so good by using only preseed, and then my RE told me to stop. He said if CM is a problem, then a couple drops of mineral (baby) oil is all you need.