You are correct. And yet you have completely missed the point.

They are not mutually exclusive. And yes, the cofounder is more important.

Today's the deadline and you have a beta product and no cofounder. Do you apply or not? More seriously than this YC stuff, do you stop working on a business idea and execution because you don't have a cofounder? Or do you continue forward, constantly looking for a chance to find one?

EDIT: I see you've edited your comment to include a YET. At this point, seems like you are the one imposing a false choice here: the YC route and all other ways. There are many options and paths and most of them don't require you to pick one or the other.