Yes, I see it as a fact that DnD has major themes involving the gathering of power. I also see it as a fact that Tolkien's work has major themes of the rejection of power. Those two things are at odds, they are literal opposites.
And, it doesn't matter that it is a "player-facing theme" because it is fundamental to how the game works and is presented. You could say Tolkien's theme was "reader facing" because it wasn't a racial drive either.
And actually, there was no leveling up for Sam and Frodo, the two who did the most good. They didn't really learn any new skills or gain any new powers. In fact, for the vast majority of the time, Sam and Frodo don't encounter any threats. The biggest is Gollum, which isn't a combat threat and is much more about the interpersonal relationships.)
I really don't get your usage of the word "fact". Like, you realize that it means something different than "interpretation", right? Whatever, moving on.
So in your opinion, Frodo, Sam (and let's say Gollum) could have been magically transported from the Shire to Mordor and would have performed about the same? And they gained no magic rings, no magic swords, no magic flash lights, no weird rope, no magic tree seeds, or anything other valuable thing along the way? And none of these things was used to defeat say a giant spider in her lair? Or taken back home?
Maybe we just read different books?
In either case, it seems like you've only (badly) accounted for half of Tolkien's halfling adventurers. I assume then that for Merry and Pippin, we're leaving them out because
it directly contradicts your argument... or maybe they just slipped your mind?
It does matter whether you are talking about themes for your world vs. themes for your protagonists. The Fellowship and D&D PCs are the protagonists. These would be your apples you should be comparing your apples against. And, as it turns out, they
are comparable.
Otherwise your argument is "the halfling heroes in Tolkien's world rejected power (which is kinda untrue). D&D halfling PCs are expected to gather power. Therefore the halfling race is unsuitable"
It logically does not follow.