Digging around on the excellent Tellers of Weird Tales, I found this article on L. Ron Hubbard from Bill Blackbeard who was, at one time, the world’s greatest collector of newspaper comic strips.
I was struck by this summation of Hubbard’s Final Blackout:
“Final Blackout” begins as a sketch, a vivid depiction of military life on the blackened battlefields of a world-wide war, rising in its early scenes to a graphic presentation of this kind of experience that has seldom been equaled in popular fiction, yet it bloats and fades in the middle into a pointless rambling odyssey in which a single man named simply the Lieutenant, plays God, and, wholly invincible, carves for himself out of the hulk of war-devastated England a throne upon which he can receive from the entire populace the same homage and worship he received from his men on the battlefield. This is not, of course, the avowed purpose of the Lieutenant, but it is subconsciously Hubbard’s, and its obsessive emergence ruins the body of the novel, logically and artistically. We can accept the invincibility — within limits — of the Lieutenant on the battlefield, where his survival after years of combat has proven him a capable soldier, but that this invincibility can be turned to the solution of any social problem, or the downing of any moral or economic obstacle, is, as presented, beyond the reader’s ability to swallow. It is Doc Savage; it is Superman; it is the pith helmet triumphant; but it is not effective fiction. This is a case where the development of a truly believable character of superior mental and moral endowment, rather than a soldier-savior-stereotype, would have made a fundamental difference and saved a potentially powerful novel, but such a character is beyond Hubbard’s ability to create—or understand. “Final Blackout” is a wish-fulfillment fantasy for Hubbard, nothing more.
MarzAat 
I have to disagree with the author of that quote. Blackbeard simply doesn’t like how Hubbard handles the Lt and thus outright dismisses the entire book. To me, the words “truly believable” are the clue as to why I think that. It’s a bloody piece of fiction meant for readers’ enjoyment and their wish fulfillment. To expect anything more is to stand in place of the author and dictate what they may or may not write AND to dictate what kind of book readers may or may not enjoy. It is that kind of attitude (telling me what I am supposed to be getting out of a book instead of what I actually am) that puts me off most vintage sf reviewers. Blackbeard might be the nicest guy ever and if I was talking to him, his points might not be hubristic at all. But there is no intonation in the written word and thus I am left with my initial impression of him.
Don’t get me wrong, I won’t be re-reading Final Blackout after my (semi)recent rereads of some of Hubbard’s other works. If I did re-read, I might think it was a piece of trash too. But it wouldn’t be for such an esoteric, self-centered reason as Blackbeard gives.
Ahem. I am now getting off my own soapbox.
Sorry about that. I just get really riled up when people get so super serious about fiction that is meant simply as a way to escape for a couple of hours. Which is ironic 😉
I myself liked Final Blackout and didn’t have the same impression as Blackbeard. I’d have to re-read it again to see if my thoughts would change.
That quote is drawn from a whole essay that, in a sense, psychoanalyzes Hubbard to argue he shouldn’t be psychoanalyzing others via Dianetics and Scientology.
Blackbeard does seem to like Fear (which I also liked) and Typewriter in the Sky (which I haven’t read).
I sometimes post other reviews of books I’ve covered to give my readers different perspectives, not because I necessarily agree with them.
And, to be honest, how often do reviewers/critics actually sway readers in their opinions of books they’ve already read and enjoyed? (They do have some effect in publicizing works and getting people to try them.)
For instance, I could point out the overreliance on coincidences in the plotting of Edgar Rice Burroughs. It’s not going to change the mind of a single one of his probably millions of fans even if they acknowledged the point.
In fiction, especially fantastic fiction, believability is, as you said, not necessarily a bar to enjoyment. And, if you impose it as a critique, an item on a checkbox of good and bad, it’s far from objective. A reader brings his own experiences, his own political views, and his own knowledge of history and human psychology to that determination. And, of course, even on a mass level, believability can be affected by the passage of time.