Indeed, it's also a matter of actual vs imagined competency. What is the point of contributing to a project if someone with an outsized notion of their range of skills can come in and botch up previous work?

The issue is whether the person modifying or reiterating a work is competent to do so; We hear all about it with programming, but there is such a thing as "cargo cult design" too.

Also, I don't see it as whether a specific design contribution is "a work of art", with all its associated assumptions of involubility; in this context design is ever changing according to the evolution of a project.