"Actually, startup ideas are not million dollar ideas, and here's an experiment you can try to prove it: just try to sell one. Nothing evolves faster than markets. The fact that there's no market for startup ideas suggests there's no demand. Which means, in the narrow sense of the word, that startup ideas are worthless"

No, this is flawed logic. If you try to sell an idea, the act of selling it means it's not worth anything, because the worth of an idea depends on peoples' willingness to keep it secret.

Articles saying ideas are worthless are a dime a dozen, because great ideas are so scarce. Most decent ideas need great execution, and a lot of great ideas need good execution since they are easily copyable (so if they don't gain a ridiculous amount of traction, someone else can come win the new space).