Can't hurt. If YC thinks YC founders are smart, and YC Founders think your app is cool/well-done, it's likely that YC will give a more serious look to what you've built.
(disclosure: I've never applied to YC. I think I'm too old!)
(disclosure: I've never applied to YC. I think I'm too old!)
Humans are not infallible machines. It's like playing chess against someone: if you play you always have a chance, and your chances are only ever 0% if you resign.