It's not exactly a trivial point - it supports my larger point by showing a history of unintentional discrimination within D&D specifically (unless, I suppose, one wants to argue that this was intentional, I guess?). It was both not really the intent of these well-meaning writers, but also still the effect. It wasn't conscious.
This makes an important point: you can have effects that are bigoted without actually being aggressively bigoted yourself.
That's important because it's counter-intuitive. It's easy for us to presume that, you know, if we didn't mean to offend anyone, than anyone who gets offended is pretty much over-reacting by definition. It's not like TSR meant to be racist, but someone who rolls their eyes at that paragraph and says, "yeah, that's actually kind of racist, guys" is still right. It doesn't mean that TSR was being staffed by KKK members out of Lake Geneva, but the fact that it wasn't meant to be offensive doesn't change the fact that it kind of is.
That's worth mentioning often in part BECAUSE it's counter-intuitive - it's something easy to forget. If it's something that happens to TSR circa 1989, it's also something that probably happens to people today in some way (even if not in the same way).
I was using it to illustrate the point that we can transform the often-kind-of-repugnant fantasy that we cull from as source material into something that is better than its source material in that respect, and one of the ways we can do that is by telling stories that feature things that would've been unthinkable in 1989 or 1919 or 1890 or earlier - things like black PC's. Or a tragic lesbian love-triangle. Or some random gay commoner. It runs counter to the argument that "this doesn't come up in D&D" by saying that sometimes having it come up in D&D is absolutely what you WANT.
It also serves to illustrate a point about vigilance: if you can cause discriminatory effects without holding an ounce of discrimination in your heart, it's important to keep an eye out for when that happens, and it's important to be able to correct yourself when you've done something a little bit awful, even if you didn't mean to, because you want the effects of your actions to line up with your intent.
An explicit policy of inclusion like WotC's or the OP's can serve to enhance that vigilance.
So pointing out that D&D was sometimes a bit awful about these things in the past is in part a call to learn from that history, so we don't repeat its mistakes and arrogantly presume that if we don't mean for it to be offensive, then it shouldn't be taken to be offensive. It's also in part showing that we aren't tethered to the past for our new stories - that it "not coming up in D&D" might be part of why you MAKE it come up in D&D, because there's awesome new tales to be told and adventures to be had when you look at D&D through that lens.
