Before responding I want to clarify MY personal definitions.
Single-a person who is completely unattached to anyone, having no loving relationship, on their own.
Polyamory-a love style in which a person has a mutual loving and committed relationship to more than one person which can and usually does include a sexual relationship. Commitment does not have to include marriage or a previous agreement of monogamy. It is just a word used to mean that this is a relationship based on emotions and not based on sex.
As I believe being poly is in the nature of a person, I'm sure there are many poly oriented singles out there. But it is MY feeling that, once any relationship is started, that person is no longer single (by MY definition). They may be "dating", "in a relationship", "seeing someone", but they are not "single". Therefor, to ME, there are plenty of poly-oriented singles, but no practicing poly singles.
So the idea of several single, poly-oriented people coming together and a practicing poly relationship forming by mutual agreement from that, seems like it would be a very rare thing. But the idea that an initial two individuals coming together with the agreement from the beginning to leave the relationship open to poly seems feasible. It is (in my mind) like comparing searching for a unicorn to developing a V within couples.
I wonder if many people feel the same and are simply confused by the use of the word "single" to mean something other than what I have stated. And, therefor, singles become a marginalized section of the poly community? Do you mean something different when defining "single" than I do? I'd love to have more clarity of thought process on this.
I'd rather be hated for who I am than loved for who I am not.