I'm not offended by your perspective because I don't think you're trying to say you are distrustful of my integrity in my sexuality or that you think I am in any way less than you because of what you described. I totally understand where you're coming from and as much as I hate how persistent that attitude is, I can't fault you for it.
That being said, I simply find it hurtful. Again, not specifically of you or of anyone else, but just as a phenomenon. I just don't understand why, if I am able to have a deep, meaningful connection with someone, it should matter what gender the other people I've had connections with in the past are, or how many there were.