I completely agree with you, I'm currently in a friendship with a lovely woman who I had strong romantic feelings for at the start. I was honest with her about how I felt, and she was honest with me that she just wanted to be friends - at that point, we respectfully cut contact with each other to honour each other's relative positions.

A few weeks later, I re-initiated contact because the intensity of my romantic feelings had subsided and I missed her as a friend. Our friendship is developing nicely. If I'm completely honest (and I have been honest with her), I still have a few romantic feelings but these appear to be fading away over time, which I hope will result in a lovely friendship with a kind person. I'm also actively dating.

So the author's advice is great but not always the final answer - I feel it's important to be open and understanding towards other people and relationships of any sort.