“Like obviously we need to make people know things exist, it makes financial and logical sense, etc.“
Why is this obvious? I know it's so normal that me asking seems weird but, is this really how the world has to work? Can we not imagine a world without ads? I'd like to at least try.
A conjecture is a problem that is expected to be true but has not been proven. So it remains a theorem because it has already been proven. What they did is to prove it in a new way. New proofs could just be interesting or they could provide a new way to think about other un proven problems.