Erm… Polyamorists tend to talk about how relationships work for them, often including the observation that that advice also works for monogamous folks.

If you choose to read things which polyamorous people write about relationships, you can’t really get in a huff because we write about the techniques that work for us. I don’t think I’ve ever heard Dan (or anyone else who’s opinion I value worth a damn) try and state that polyamoury is inherently better than monogamy in the general case.

Poly people sometimes write more about relationships, and muse more about the techniques that work for them. But that’s because people tend to ask us more questions about how our relationships work, so we assume there’s at least some interest in what we’re doing.

Also, I don’t think your guitar analogy is very apt. I would say that having lots of lovers makes you think more about relationships, how they work, what they require, what you could and should be doing to keep others and yourself happy. In that respect, it would be more apt to say that having lots of lovers is to relationship expertise as performing in lots of different plays is to acting skill. It’s not the same as innate skill, but it can help.