I think that's going a little far.
I definitely think people use "evil races" as a way to paint the bad guys with a broad brush. The thing is, I don't think anybody doing this thinks beyond that. Its literally just red team vs blue team. Whether they will begin the encounter as hostile or neutral/friendly. I don't think people are interested in the morality any more than they're interested in the morality of killing a moblin in Zelda or stomping on a goomba or koopa in Mario. They're red team, and you're blue team, and the game is to fight them. Playing D&D like it's a tabletop video game doesn't mean you're explicitly interested in glorifying immoral actions. Not every game of D&D is necessarily roleplaying at all. Lots of tables are still just running it as a dungeon adventure game.
Don't get me wrong. There's absolutely a problem with portrayal of a races as always evil in the materials for the game, especially given the language used. It's a needed improvement to the game to correct that problem. Even so, if you're trying to simulate a real world, you're going to want to avoid all that probably to the extent that your game should not use alignment at all.
And we largely still do "always evil" with things like undead -- even sapient undead -- or certain monsters like beholders or mind flayers, even when we've identified "always evil" races as bad. There are still NPCs that are pretty safely always kill-on-sight. In the case of mind flayers, it's probably a good idea to destroy that elder brain nursery pool, too. It's not like the rest of the game is completely without any dehumanizing elements of the monsters. D&D is a game with sapient monsters. That inherently has some odd side effects. Each table needs to draw that line, but the game itself should avoid dehumanizing whole peoples wherever it can.
Edit: Clarity.
It's also worth noting that Gygax
absolutely did believe it was totally right and proper to slaughter the women and children of "evil races", and went as far as to quote a genocidal ultra-racist writer in support of this viewpoint.
So when you say it's "just painting with a broad brush", and "people don't think beyond that", I would strongly question that at least in as far as applies to the whole deal where D&D (unlike a lot of RPGs), has a bunch of "evil races" which have non-supernatural reproduction and growth and so on. I think that Gygax absolutely did think beyond that and was totally happy with that situation.
When people merely carry on this "tradition", yeah I think that tends to be an unconscious replication of the situation, and indeed, if the person is forced to think it through, they may well rejected the Gygaxian "genocide is the answer" approach. But not always. There's an incident I've talked about before early when I was playing D&D, when we had just such a scenario inflicted on us by a 1E DM who had moved to 2E. We fought and killed some orcs and there were orc toddlers, who were just cowering. We the players were all like "Awww sad, we need to take these lil orphans to a monastery or something", and the DM had his DMPC be all like "No thou mustest killst them!" (why the DMPC talked like that I have no idea but there was certainly a lot of "thou") and explained that unless we did we weren't being Good. There was a lengthy argument of all players vs the DM. We all thought he'd gone completely mad, and the DMPC got told "try and stop us", and whilst he could have wiped the group, the DM wisely chose not to, knowing that would be the last time he ever got to DM (spoiler: it was anyway). What we didn't know at the time of course that, according to EGG, he was
completely right! Which is funny given a major pillar of our argument was that there was no way D&D was intended to be interpreted that way because it wasn't written by genocidal lunatics (half the group being Jewish probably didn't lay fertile ground for "genocide is cool" either, one might note).
Being online in the early 1990s I saw similar viewpoints promulgated frequently by some DMs, particularly those who still played 1E, or only reluctantly had switched. The majority viewpoint was clearly against them, but I saw lengthy arguments, which clearly were thought-through, about how it was totally righteous to slaughter defenceless women and children.
So whilst I agree that most people who have "evil races" aren't intentionally promulgating some well-considered pro-genocide view, there definitely have been some, including EGG, who absolutely did see it that way. As such it's not surprising that WotC have come out so strongly against this view that they're actually changing how D&D is presented so this view can no longer be attributed to them. They're honestly lucky that some of the stuff EGG said didn't come out nearer the start of 5E, and it still isn't well-known, because the backlash could have been... bad.