BOB killed Laura, Ruth was decapitated by a portal, Diane and Audrey were raped by "Mr C" - perhaps these are all the same kinds of fantasy.
This is a wonderfully evocative closer, and I don't think your thesis is off-base whatsoever.
It is possible to just see this as the result of people trying desperately to understand season 3 through the framework of the old show rather than as its own beast, but I think there is something to the comparison.
Season 3 is radically different and obstinately so aesthetically, but I'm not convinced it's very much different at all from the old show in a plot-sense. In fact, from my POV the mythos, themes and philosophy of the show seem inextricably wed to what's been set up already. When Lynch & Frost discussed in interviews how it was they were able to return for a new installment, they described it as "finding a way back in," and I think that language alludes to the idea that the TP world is a set of ingredients and, one could even say, rules.
For instance, to apply some of what your post is getting at to Frost's contributions, much of what TSHOTP and TFD change is consistent in purpose and theme. The endlessly convoluted soap-opera fashion Annie, Norma & Vivian's backstory is altered introduces an unreliable narrator quality to how characters historically presented information in the
show itself, changing the context to be a layered and complicated lie. Josie's backstory, in being fleshed-out at length, broadens what was already a known lie, but also makes some truth-presenting reveals themselves lies. Ben's heel-turn to goodness turns out to be a lying prelude to an actual heel-turn, the motivations for why Audrey chains herself to the bank-vault also changed into a lie. As for the books themselves, the previous installments are implied to have been redacted and altered physically, making them in-universe artifacts of truth-tampering. Many frame the spinoff books as inessential or the Frost books specifically as mere re-write happy irrelevancies of indirect themes, and that's anyone's valid prerogative, but taken altogether the overwhelming thematic focus of the TP franchise is lies & fantasy & nostalgia, and to an extremely fundamental extent.
Here's potentially inflammatory food for thought: I've read many take issue with the Naido/Diane reveal in the context of political correctness; that transforming a faceless Japanese actor into a previously established white character is some kind of distasteful erasure or prevention of a significant character being non-white. I'd argue that this is a conclusion only possible with poor faith, and that there are alternatives that make far more thematic sense if we give L/F benefit of the doubt. After all, this scene is a case of your thesis topic; Cooper sees faceless skin and seemingly unearths (manifests? projects? grafts?) a face onto it that neatly (suspiciously and absurdly so) starts to tie everything together, right after an evil is supposedly felled in the most Campbellian manner. Without this reveal, we'd have been left with a Japanese body disfigured in an absurd, grotesque, debased fashion, electrocuted and flung from some of the most abstract liminal spaces of the series, a series whose newest iconic image is the testing of the atomic bomb the government Cooper works for would later drop on Japan. Our heroes, despite atrocities the series itself alludes to, are all government agents who embody wholesomeness. One of the only significant characters of color is a prostitute (a long-standing trope many a lamenting essay have protested), the other a (somewhat subverted) trope of the Native American spirit guide. In fact, now that I think about it, the Minority Spirit Guide trope is as deeply embedded in TR as in western media historically: every helper character involved in Cooper making it to his suburban fantasy home as Dougie is a physical or racial minority: the Fireman & the One-Armed Man, Naido & Jade. And going from cultural offenses to sex (glossing over mere blood and guts violence entirely, which is self-evident): our beloved character Audrey is revealed to have been raped by a version of our beloved hero Cooper, but this extreme affront of expectation and investment isn't resolved within the plot and, of all things, instead left dangling. Diane,
another raped female, is later the participant in a dark, dismal sex scene the narrative logic presents as
necessary and
good.
By the end of the season there are mounting contradictions, a pile of females wronged both physically and through metaphysics, and a quite strict focus on an extremely homogeneous 50s cultural and ethnic makeup despite taking place in modern day. I find it strangely perfect that when Cooper finally emerges after many years having gone by in the real world, his first interaction is with an absurdly coded character: a prostitute who exudes a kind of 50s nicety and helpfulness. When presented as unknowing, L/F are out of touch in some extremely egregious way. But the consistency to it is so specific I find it far more likely that they're intentional aspects of a frame of mind that TP is trying to embody and juxtapose. TV stock characters and genres are themselves lies and fantasies the culture breathes onto TV screens, the same way the series now implies
someone does so for the TP universe.