I disagree with this to an extent. I think it’s okay to tell a company that you want sponsorship. But, I don’t think anyone should seek sponsorship, until they are ready to offer a company something great.
This is from YoyoFactory ask.fm. They have told several people inquiring about sponsorship to “apply.” I think it’s like a job, it’s great to be offered one without asking, but it’s certainly okay to apply for one too: