No, but communities can set expectations, and then someone can choose to meet or buck the expectations of the community at their own risk.

A good example of this is the TodoMVC convention. Instead of making "whatever demo app you choose" a convention developed to make a Todo app, so that people could compare frameworks in a more "apples-to-apples" way. A new framework with a Todo demo would likely get more traction than a framework with a Calendar demo, because it's easier to evaluate and understand how it works.