This is true. I was circumcized as an infant, and when I started having sex around 19, I wondered why it didn't feel as good as it was supposed to. I thought I was doing something wrong. So I tried harder and harder, inexperienced as I was, and didn't learn how to make sweet, gentle love until much later. Even then, it was more for my partner's pleasure, because my dick just isn't that sensitive. It caused a lot of problems in my relationships early on. Frustration and feelings of inadequacy on both sides, because I was "~~hard to satisfy~~" literally unable to feel satisfactory pleasure...