Thank you for this analysis! I think you raise a number of important points.

I'm not even sure that "theory" is the right word to use. It's far more like ideology. The normal sense of the word "theory" is something like "a coherent set of beliefs or premises that provide a general explanation for a sizable range of phenomena". Implicit in the idea of a theory is that you're measuring it against reality.

I recognize that "theory" has a somewhat different meaning when it comes to political outlook and social philosophy, and you are using in that (correct, in context) sense here. But I really think it's a linguistic overreach--adopting a word to suggest connotations that the idea just doesn't have. "Critical Theory", for instance, would more aptly be named "Critical Deconstructive Approach"; not to say that it doesn't have some merit and validity, but when an area of inquiry starts out by suggesting that it promises more than it ever is designed to deliver, I don't think that's a terribly hopeful sign.

I agree with the take-home point: the new left, unlike the older left that mostly welcomed a diversity of viewpoints, seems focused on accepting an extra-wide diversity of individuals based on how they present, but a substantially narrowed distribution of outlooks: you can be anyone (which is an improvement!) but you cannot think outside of a quite narrow box (which is a regression!).

However, this trend is not new for the left--the era of "political correctness" strove for similar narrowness of thought. (Not that it didn't have good points about societal meanness that should be fixed...but it came along with an intolerance of different viewpoints where, for instance, questioning approach was treated with the same vitriol as questioning goals.) My read on what happened to that was that people made fun of the overreach (e.g. SNL's Daily Affirmation with Stuart Smalley was a good example) and the benefits were mostly kept while the thought-policing excess was not. (Ironic that Al Franken, who created the character, arguably ended up falling victim to that same kind of excess rather than a more moderate level of chastening.)

It's also worth pointing out that almost nobody in either party, all throughout history, has been terribly interested in effectiveness-testing their policies. But even within a general attitude of disinterest, there can be trends of greater and lesser attention to staying grounded.

Anyway, I view the new left as, more accurately, "ideology first" not "theory-based", though I accept that the latter is, in proper context, also a reasonable way to describe it.