That's a good point, but I think very often people still have hard time creating effects they want. For example good few years ago I published few shaders on Unity Asset Store (like https://assetstore.unity.com/packages/vfx/shaders/fragmentat...) and there were quite a lot of purchases (and still are sometimes).

My point is, you can create more complex effects and provide them as a tool/out of the box effect (wrapper)