I think the reason it (and Cline novels in general) are so controversial is because the political dimensions of gamer nostalgia are usually cloaked in irony, but RPO isn’t ironic for a moment. Irony acts like a protein sheath around a virus, to prevent our immune systems noticing it. The constant cringing irony around gamer nostalgia is true even of big movies like Wreck it Ralph and Pixel: they’re slathered with insincerity and sarcasm about the media they invoke.
But Cline is 100% earnest. Not a shade of guile, no caviling, no clever shading. Just pure unleavened nostalgia, and the idea that you can build your world entirely out of nostalgia.