We regularly receive more than twice as many proposals as we have slots to fill. It is tough choosing. We expect many high-quality proposals to choose from this coming year too, so we need reviewers! Be aware that as proposals may contain sensitive information, only people known in the Python/PyCon community will be invited to participate.
The proposal system assigns talks to reviewers. The more reviewers we have the fewer talks each person will need to review. Our review meetings have evolved a process which is now quite streamlined, fun (yes, fun), and rather consistent.