Sure, it happens. Especially if somebody is already well known and respected in their field.

But it is not common, and I find it frustrating how many people think they can fast-track their way to the bigger events. I've been on the committee that rejects their submissions and find myself having to diplomatically explain to them "you've never done this before, nobody has any idea who you are, you've done nothing to establish your credibility regarding this topic, and you were one of 1500 submissions for 50 available slots... sorry, kid, that's not how this works."