Then there should have been no problem with telling people, "Oh, you want to play a moderate to heavy armored martial character who is very good at killing their enemies dead? Play a Ranger. That is what you play to make that happen."
But instead, opposition to that--opposition to, as you have so blithely said, "RTFM"--landed us exactly where we are today. "Fighter" had to be at the top of the sheet no matter what someone actually wanted to play.
No, caster prestige class. Silver Pyromancer. Largely intended for Sorcerer, but Wizard and Bard can also do it, and EK/AT can as well at very high levels.
The technical term is an informal fallacy. It is not a fallacy due to the structure of the argument (e.g. the fallacy of the excluded middle is a formal fallacy because the form fails to connect the conclusion to the premises), but rather because the argument is unsound. For Oberoni, the fallacy is the claim that, because house-ruling/homebrewing/DM adjudication exists, any flaws in the rules aren't actually flaws, so the rules are always without fault. It is by and large a particular application of the fallacy of equivocation: flaws/faults/etc. are used in one sense as "errors or problems that have to be addressed," and in the other sense as "fatal problems that completely prevent play." When spelled out as such, rather than preserving the ambiguous terms, the failure to connect premises to conclusion becomes obvious:
1. A ruleset exists which contains elements that do not function as intended and thus cause problems.
2. The GM of any game can modify the ruleset to improve its function or address problems.
C. Therefore, no ruleset exists which contains elements that do not function as intended and thus cause problems.
The weaker argument, non-fallacious but also much less meaningful, is that "Rule Zero" etc. mean that no ruleset can have completely fatal flaws, because no flaw is so egregious that sufficient application of Rule Zero cannot fix it. But that claim is pretty risible--it's literally just saying, "If you work hard enough, no matter how badly made a game is, you can force it to be good. It just might take a bottom-up redesign!" Of course if you're willing to work for literally years, replacing every part and redesigning every element as needed, you can address literally all problems ever--but that's an admission that there are problems that do in fact need to be addressed, which was the point in question to begin with.
"You can fix any machine by replacing all of its parts" says very little. "No machine is ever broken because you can always hire a repairman" is fallacious--doubly so because the only reason to hire a repairman is to repair something.
The vast, overwhelming majority of my play, as a player, has been with people I did not know particularly well before playing, for a large variety of reasons. If you find a great group, then sure, friendships can flower from it. But my friend group isn't exactly enormous, and very few people in it are willing to run TTRPGs of any kind, let alone ones I am specifically interested in playing. It would be awesome if I knew literally anyone else willing to run something that wasn't 5e. I don't. Even people willing to run 5e, there's only two. Hens' teeth and such.
Haven't ever heard of the book, so I can't comment.
So, as is literally always the case with these things, you are confusing the goal here.
I don't want to make a game that does the things I want a game to do.
I want to PLAY a game that does the things I want a game to do.
The former is totally orthogonal to the latter--and, more importantly, even if I did the former, it wouldn't help me find a group. Which is something I looked for. For over a year. Gradually broadening my criteria until they became "for God's sake, will anyone run anything that can be massaged into something vaguely like what I would enjoy?" And the answer was quite consistent: No.
I tried. I'm not going to spend six months of my life on a heartbreaker that won't ever be seen by 99.99999% of the gaming community because people are creatures of habit and, to paraphrase Jefferson, all experience has shown that people will retain the things to which they are accustomed rather than doing something different, even if it would be better, let alone might be. "Better the devil you know," as they say.
It really isn't "so embedded", and this "you literally cannot please the people who are upset, so never ever bother trying" argument is pretty awful merely on its face.
When 46% of its players are dissatisfied with the Fighter class, yes, I think it's pretty fair to say that people are dissatisfied with the Fighter class.
They keep playing it because they like the idea, the concept, the theme, the intent thereof. But the execution is lacking. People are in fact dissatisfied. They also keep playing! Why would that be? Could it, perhaps, be what I've been arguing for years, which you have always consistently dismissed, that the design actually matters, even though people will continue to play something they find unsatisfactory?
"What are you complaining about? Banging on the hood a couple times gets the car going. Obviously, it doesn't need any repair work."
A machine that requires percussive maintenance to function has a problem and needs repair. That it can be cajoled into working through percussive maintenance does not mean there isn't a problem.
Is that, maybe possibly perhaps, because people aren't super interested in playing utterly unremarkable, do-nothing commoners? That when they hear the idea of fantasy adventure, they'd much rather be Aragorn than Nameless Rohan Citizen #37?
We tell stories about people who are interesting to focus upon. Farmboys whose true fathers are evil wizards leading the armies of the Empire. Young women whose inheritance is guarding the barrier between life and death. Mages marked by the evil of the dark wizard who slew their parents. Heirs to forgotten crowns and constructs yearning for purpose built by mad geniuses. Comfortable landed gentry who feel the call to madcap adventure...or to carry a burden greater than any other.
D&D bills itself as high fantasy high adventure. Has since at least 2e, probably earlier. Not really sure what you expected people would think they'd be getting. Planescape was driven, in part, by making a setting that melded high and low together, with the grit and grime of Sigil and the weirdness and power of the planes all in one package.
Hmm...I wonder if you can import material from DMsGuild to D&D Beyond. That would be neat, if it was possible. 
WoTC does control the Guild to a certain degree.
Admittedly it was to try taking the game in a different direction for a while (weird west or space fantasy), but still.
