Not only that, but reverse the scenario and see how it plays out. What if a cishet white dude said he couldn't relate to a comic because the heroine was a gay black chick? REEEEEE REEE REEEE sexism soggy knees! And, actually, it would true, to an extent. So why is do EF readers have trouble relating to a character because that character differs from them? I would argue that they either lack imagination, empathy, or an interest in the subject matter. I'm an avid reader of both text and graphic novels, and have never had a problem relating to characters with different genders, sexualities, races, or backgrounds... and the reason isn't because I'm special, it's because I tend to pick authors who know how to write good characters. Writing is all about making a great character, not finding the ideal reader for the character you've already made.
But hey, if it's that important to you, stop blogging and actually make your own comic character. It's remarkably easy in this day and age. You can think up a character at breakfast and have their first adventure online in some form by dinnertime (note: I strongly encourage putting slightly more effort and thought into it, but that's another can of worms) If you want an identity-based character, get off your ass and make one, no one is stopping you. Complaints like this are really only a sign of the author's laziness.