Actually, your argument was a misrepresentation of the texts, and your reply missed what I was trying to say.
You sound like you're saying the source shares the blame for giving bad advice, because it advised the players to outflanks. Thing is, that's not what a good book on strategy would do. Or to be more precise, it's only one of a very large number of things that it would recommend as part of victory, and not always the right thing to do. Books like the Art of War go into great detail on when and why you should try to outflank, and how you should go about it.
The problem is not with the idea of outflanking itself, it's with the execution of that maneuver. The Art of War never says 'outflank just because you can'. Outflanking is just one of may options available, and isn't always the correct one.
Speaking of fallacies, your argument is actually a genuine strawman. Your line of reasoning for arguing against military texts seems to be this: 1) military text says outflanking is good. 2) outflanking doesn't always win. 3) ergo, military texts aren't very useful, because they don't always work.
You are misrepresenting the texts, and using that to dismiss the text. No text like the Art of War claims to be a simple checklist of "do this to win". They do say stuff like outflanking is good, but they don't claim that execution is unimportant, nor do they claim you should do it just because you can. They're saying, "if you do it right" you can get a big advantage. Your argument relies on ignoring that "if you do it right" part.
The 'auto-win' part of my statement is really irrelevant. Nor is my statement actually about the effectiveness of outflanking. If all you're getting out of my previous statement is an accusation that you think outflanking is an auto-win, then skip that part and read it again. I posted because of the funny sentence I put in there, but if you want to get serious and start throwing around accusations of logical fallacies and irrelevance you could at least actually read my comment for its actual content.
Even disregarding that, your statement against mine is self-contradictory. You claim that texts share the blame when their strategies don't work, presuming that they take special claim to aid in victory, then turn around and say that they don't take said claim. So which is it? Do the texts claim to ensure victory, and thus share the blame and should be ignored? Or is the blame solely on the players due to chance and misuse on the behalf of the players who lost, because the texts don't claim to be an auto-win. You claim to believe the latter, yet your argument relies on the former.
And if you're trying to say that outflanking is useless, you are incorrect. It is less useful in 40k than in real life, because there are no rules for crossfire and such, but it is still quite useful for controlling your opponent's movement and the like. But just like any other tactic, you have to execute it well if you want it to be effective. As Scott Adams says; "an idea is only as good as its execution. The idea itself is worthless."