Pretending to lose can be a good move, and if you are able to play it at the right moment, it makes you stronger.
Did Quirrell ask Harry to accept some unrepairable damage? No. It was only about signalling, and temporary pain (any resulting damage is guaranteed to be healed magically later). Quirrell taught Harry that signalling defeat is not the same thing as being defeated. Just like Voldemort, pretending to be killed by a baby, is not really dead.
(I agree that asking for a worthy adversary is suicidal. Having a sparring partner can be useful, but you should be able to destroy them reliably, when necessary.)
EDIT: Though, you have a good point. Willingness to simulate defeat may reduce emotional barriers against (real) defeat, which in some circumstances could weaken one's resolution to fight. Humans are not perfectly logical; when we do something "as if", it influences our "real" behavior too. That's the essence of "fake it till you make it" self-improvement... or perhaps, in this specific situation, self-weakening.
The next discussion thread is here.
This is a new thread to discuss Eliezer Yudkowsky’s Harry Potter and the Methods of Rationality and anything related to it. This thread is intended for discussing chapter 84. The previous thread has passed 500 comments. Comment in the 14th thread until you read chapter 84.
There is now a site dedicated to the story at hpmor.com, which is now the place to go to find the authors notes and all sorts of other goodies. AdeleneDawner has kept an archive of Author’s Notes. (This goes up to the notes for chapter 76, and is now not updating. The authors notes from chapter 77 onwards are on hpmor.com.)
The first 5 discussion threads are on the main page under the harry_potter tag. Threads 6 and on (including this one) are in the discussion section using its separate tag system. Also: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14.
As a reminder, it’s often useful to start your comment by indicating which chapter you are commenting on.
Spoiler Warning: this thread is full of spoilers. With few exceptions, spoilers for MOR and canon are fair game to post, without warning or rot13. More specifically: