The goal of building a fictional world isn’t to build a world. It’s to build a metaphor. And the success of the world you build isn’t measured by how complete or coherent or well-mapped the world is. It’s measured by whether the world and the meaning map onto each other.
Arguments about worldbuilding in SFF don’t generally focus on metaphors. Instead they often focus, somewhat paradoxically, on realism. How can you best make a world that feels as detailed and rich and coherent as the world you’re living in now, complete with impeachment trials, global warming, pandemics, pit bulls, and K-pop? Should you, in the manner of Tolkien, systematically construct every detail of your fantasy realm, with maps and histories and even complete languages? Or should you leave spaces to suggest vast uncharted bits? Maybe sometimes it’s more evocative not to tell your readers what lives on every part of the map, or what the Elvish means. As China Mieville says, “A world is going to be compelling at least as much by what it doesn’t say as what it does. Nothing is more drably undermining of the awe at hugeness that living in a world should provoke than the dutiful ticking off of features on a map.”