There are some subtleties in Gatsby that most people miss, and isn't even addressed in the article.

Jay Gatsby (James Gatz) is probably Jewish.

Nick Carraway is probably gay, but at least bisexual.

Both of these traits forced people into lower castes this era in high-status society. To me the lens of the book is repeatedly the failure of "if only I can win them over" slowly becoming the unsatisfying "these people were always assholes." Whether it's parties, a potential spouse, or important friends, the entire concept of class structure is poison. If people are good people, it shouldn't matter how they present themselves... that's just what I've always taken away from it. It seems like a theme that someone with Fitzgerald's background would want to convey, especially someone with that background who enjoined the company of people like Hemingway. And I think that's been a theme of American culture since reconstruction.