One of OP's early theses is that the left is all about economic class, but can't admit social classes exist, so conflates them with economic class in order to talk about them.

Who exactly can't admit social classes exist? Karl Marx was very aware of the existence of status classes running counter to economic classes (the status of wealthy jewish people of low-status in Europe was fascinating to proto-sociologists, many of them jewish), he just theorized that economic class was "the big one" from which the others stemmed. Jews as a social class weren't sprung from the ether, though.

Max Weber, another leftist considered one of the fathers of sociology, named the "Status Class", related to prestige, one of the three main ones along economic and political allegiance ones.

Modern intersectionalists routinely bring up how arbitrary many of our social predilections seem to be, such as "tan white > white > black", or "pink is for girls", and look at these chicken-and-egg situations trying to figure out where they started. Where does the impetus for this bloggers' parents verbally check[ing] us in a heartbeat if the vowel in our "to" started getting too schwa-like come from?

The big mistake made by the author of that piece is the idea that they can isolate class and talk about it as its own thing. It's a very scientist-like analytic-approach (kinda like Marx isolating economic factors in spite of the others), but seeing as the author is openly against abolishing classes, it seems to be in service of discrediting the efforts of the economically-conscious-left ("even if you abolish economic classes social classes will prevail, so don't bother") rather than as an honest intellectual inquiry.

With this line:

> Please note: for purposes of this discussion, the topics of race, ethnicity, gender, immigration status, and native language are all derails of the topic, which is class.

The author seems more concerned with prevailing than with being correct.

If your benchmark for analyzing the modern left is a collection of theorists from a hundred years ago, you're going to misunderstand a lot more than just this.

If you think "left" is precise enough category to talk about meaningfully, you're going to misunderstand lot more than just this.