Your "guide" is rubbish. Depersonalization disorder is per definition not a symptom of something else. When depersonalization is a symptom then it is refered to as "secondary depersonalization". You are using the diagnostic criteria from the DSM-5, but you did not even understand them correctly.
Likewise there is no sound evidence for depersonalization being an "ancient evolutionary mechanisms" as you say. Your claim that it was a response to stress, anxiety, and trauma is also way overblown, since there are many other causes for temporary depersonalization and there is no good argument, why it should be regarded as specific to stress. In particular even if depersonalization could be regarded as stress response or "defence mechanism", this would not need to apply to depersonalization disorder similar to the dichotomy of acute and chronic pain, where the former is a defence mechanism, but the latter clearly is not.
There is also no real evidence for the notion that some kind of "loop" of rumination and anxiety is keeping depersonalization alive in depersonalization disorder. This idea has been circulating around even in professional circles for more than 20 years, but this doesn't change the lack of evidence. Psychotherapists even tried in a small study to treat patients with depersonalization disorder using a treatment built on such a theoretical framework, but the results were mediocre at best.
You think you figured depersonalization out, but you don't know a thing about it. You are just another recovery nazi, where it's difficult to decice, whether your hubris or your messiah complex is higher. It's unfortunate that someone like you became moderator of r/dpdr, since you will surely turn it into a censorship hell, where only "positive" posts are permitted and "negative" or "toxic" people - people who don't fit into your "everybody can recovery"-ideology - will get banned. I have been witnessing this for years. It always goes like this with the likes of you.