Identifying what questions to ask is often much harder than answering them. Proposing new theorems - and new areas of investigation - is what expands boundaries. Proving them is confirmation.

Once the Pythagorean theorem was proposed, many different proofs have been identified. In art, once a new style is created it's often straightforward for others to replicate. In physics, the idea of Relativity was what enabled the design of experiments to demonstrate its correctness. Proposing the idea is what's essential.