Completely true. I've written about this subject myself, as a lot of fantasy writers think worldbuilding with insane levels of arcane detail is what makes a great fantasy novel. It isn't. That's background, and adds believability, but it isn't the most important thing. The most important aspect is finding universally relatable themes and placing them in that setting. That's why The Lord of the Rings isn't really about elves, wizards, orcs, and so forth. It's about friendship, loyalty, courage, temptation, sacrifice, good versus evil (not just externally, but the evil within oneself), environmental catastrophe, the horror of war, growing up, and the bittersweetness at the end of an era. All universally resonant themes.

I wrote more about this here, if you're interested. :)

https://medium.com/writers-blokke/what-makes-a-great-fantasy-story-af184519457d