Anyone can come up with an idea. Lots of people can build a product for a wage. Finding someone who will develop their own idea is what's valuable. The question is whether people who can deliver technically want a partner who can deliver marketing and are willing to take the risk finding them.
I think that's an interesting take, even if not meant by hmexx. Startup ideas as publishing. $5000 advance, $3000 guaranteed marketing (of unknown value), and 50% royalties. I'd write a book for that rate. Why not an app?