@Aaron, thank you so much for your well phrased and thought out response to this. This issue can get very emotional for everyone involved and so many people want to jump to the rescue of their community that they don't consider that saying "I've never seen it happen" diminishes the legitimate concerns of those who have had it happen to them or have witnesses such occurrences. I've previously abstained from this conversation for exactly those reasons; I didn't want to add to the noise without bringing something constructive to the conversation.
Having run a retail game store in the past I can say that for my part while I have never personally witnessed major transgressions (but I do know they occur in some communities), I would witness and hear minor discriminations on a daily basis that seem like nothing at the time but add up to an environment where some don't feel welcome and where larger infractions seem acceptable. Calling something "gay" in a negative way or using casual slurs against one's sex, race, or sexual preference (the common, specific terms I won't write here), even in a joking matter that doesn't directly apply to anyone involved, is not acceptable and allowing it to occur within your community can normalize it so that people don't realize it's unacceptable behavior. When you hear someone in your community say something inappropriate it can be as simple as saying "Dude, not cool. Don't say stuff like that." to get someone to realize that what they thought was just friendly banter is in reality unacceptable language.