I usually just lurk around these threads and never post anything, but I'm going to jump in here and say that, if I understand what you're saying correctly (which I'm not sure I do, though I've read your posts in both english and french), I think you're misunderstanding the purpose of HPMOR? It's not a hate-fueled enterprise, and EY has said before that he's not writing MOR to mock the Harry Potter series (I think in an author's note he once said, and I'm paraphrasing here, that he completely understands the plot holes and irrationality that exist in HP as it's a series of books for children, and he thinks that writing a novel for children is probably more difficult than writing a novel for adults). And I don't think EY (or any rationalist, for that matter) is trying to stop people from having irrational dreams (or even holding some irrational beliefs); it is at its core about logic, and patterns of thinking, and seriously examining why you think the things you think and believe the things you believe.

And concerning your LOTR example (and I say this as someone not particularly invested in LOTR and I can't comment on that interpretation), it is possible for a narrative to contain allegorical elements while still being a story, and it's possible for readers to interpret meanings from a text that weren't intended by an author, and the lack of authorial intent doesn't mean that those meanings aren't still a valid reading of the text. HPMOR is a teaching tool for rationality, but it's also a story, and we're still meant to enjoy it. Neither of those things threaten the other.

Given LessWrong ideals of rationality there nothing irrational about having a dream to be a professional singer provided the dream makes one happy and one's goal is happiness.

PS: When speaking in a foreign language in which one isn't very skilled, it's useful to keep sentences short.