The "we can't let you delete your account, otherwise our entire system breaks down" thing is something I simply can't understand as an argument, especially on YCombinator's HackerNews.

I already asked for deletion of all my comments/submission and the account, but never got a response. I'd not be ok with having my account "disabled" like on Facebook. This is not a police database or a highly critical system where deleting records is illegal, dangerous or anything. People just submit links and talk about it, that's all and we all try to be friendly to each other here as good as possible (not always though).

I believe that letting people go and opt-out, or delete their account is not a luxury or an option, but a human right and part of a good customer service too.

Even if you could they are probably archived in so many other places that it would be fairly pointless to do so. Never post something on the Internet that you might later want to delete or completely disconnect yourself from.