Here is my two units of currency, from some one who qualifies as a non-native to English, foreign type.
I agree with the assertion that there is a propensity toward a certain type of story here. For example, I kind of find all the do-over stories super annoying. But having read all the posts in this thread, no convincing case has been made that there is a formal, structural impediment to there being more types of stories, by a more "diverse" group of author.
There is certainly, in my view, no justification for someone to look at the site and immediately "head for the hills". I understand how an author might post one or two stories, not get the sort of response they were hoping for, and not come back. But suggesting this site is such an obviously ethno/hetro centric, dick-swing barn of a place that people feel justified in not even engaging with it doesn't resonate with my experience - at all.
Again, I am not suggesting - in anyway - that authors and stories on this site don't incline toward certain archetypes. What I am saying is that in an open environment where authors are free to post stories and users are free to read/vote for the ones that appeal to them, there aren't good solutions available for significantly altering this dynamic.
What can be done and has been suggested during this thread amounts to dancing on the head of a pin. Unless one is prepared to overtly alter what stories are available and/or are presented to users - when searching for example - in order to push more exposure for certain, designated categories of story/author, we aren't going to be getting anywhere. All sides have - rightly - made clear they don't want to see solutions like this and I would add that it would be more than counterproductive to do so anyway.
So we can keep going in circles and say we care about and are discussing diversity, but it isn't a question of not acknowledging or wanting to talk about it. It's that no one is presenting substantive solutions nor does it seem like they are able to.
In life as in online fiction libraries, if your kink, preference, point of view, gender, race, whatever, isn't at any given time, the prevailing one, very little else can be done after overt, formal hindrances that exclude them have been removed. All subsequent acts of inclusivity and what-not amount to tying someone's shoelaces for them and claiming you helped them climb a mountain. More often than people are comfortable acknowledging, the 'help' is more akin to tying a person's bootlaces together and still claiming you were instrumental in getting them over the peak.
If authors are getting any amount of abuse, by all means, come down on those doing so like a ton of bricks. But if authors under-represented here don't see a need or value in posting to this site, no amount of handwringing, ineffectual tinkering, or bandying about of slogans is going to achieve very much.