No, I know for a fact it is not true. Look at literally any modding scene, look at the good and popular mods. First of all, they are free. They are good because people do it as a hobby and they do it for themselves, first and foremost. They want to shape the game into something they enjoy more, that is why they mod.
Introduce monetization into the equation and anyone who wants to monetize will aim to quickly put out content they can monetize. That...