I not a Kauffman slappy (for example, Synecdoche was one of the most torturous movies I've ever sat through), but I do love Adaptation. I'm not sure I agree with your assessment that the ending is "Kaufman's way of saying 'truth and purity die in Hollywood'". (Maybe the original script was changed for the movie). But in the movie (spoiler, so for anyone who's interested, don't read on), Donny and John LaRoche both die, LaRoche by an alligator attack. Earlier in the film, McKee chastises Kauffman to not ever under any circumstances use deus ex machina as an ending, which obviously having an alligator pop out of nowhere is an extreme example of deus ex machina (even, as you point out, absolutely ridiculous like Monty Python). Kauffman systematically violates every one of McKee's "rules" except for his central tenet that characters have to change, or else what's the point of even having characters? Donny dies, and Charley is finally able to get over himself and confess his love for Amelia. I don't know anything about insider stuff, or any of that, but to me, it's just a really interesting and beautiful story about the struggle to find beauty, love and passion in a world that doesn't always reward those things.