Sorry, no. I'm not going to engage with this premise because it's inherently faulty. I did not say that D&D's exact version/style of gnomes is present in folklore or pop culture. Just that there are obvious folklore creatures that are very similar to major aspects of D&D's version of Gnomes.
I will give you some examples of creatures that are very similar, though.
Santa's Elves are very, very similar in many ways to Rock Gnomes. They're short, pointy-eared, kind-hearted tinkerers/inventors. I'm not claiming that they're exactly the same, just that there are clear similarities between the two. Sure, they're not named "Gnomes", but that's irrelevant to the fact that they're quite similar creatures.
Same with Snow White's Seven Dwarves. Those are way closer to D&D's Gnomes than its Dwarves (mostly similar to Svirfneblin, actually, as they specifically mine for gems).
And, yes, World of Warcraft's Gnomes almost definitely came from D&D via Dragonlance, but they're still part of a popular non-D&D franchise and quite similar to D&D Gnomes. They've been around long enough to be fairly well-known.
I do not disagree with you here. I do see that halflings and gnomes are probably too similar to be distinct races. I do not care if Gnomes are a separate race, so long as there is some option to play something similar to them. I don't care if they're combined with Halflings, Elves, or Dwarves, as all of them have huge similarities with at least one Gnome subrace. I really, really like Gnomes, but I am not so protective of them that I want to avoid them being folded into another race. I'd only be upset if they were completely dropped from the game. So long as there are guidelines to play a gnome (or something similar enough), I'd be perfectly fine with it. I'm as annoyed by redundant races as you are.
I can see why people don't like Gnomes being redundant/overlapping with other races. I like them even though I largely agree. And lots of people like other races that are mostly redundant (you remember the Halfling thread), to the extent that they will fight online for 200 pages arguing why they should be distinct races. I am not one of those people and I would be 100% fine with all of their most important traits being combined with another race.