I think it's very clear that there are many ways to produce good art. I don't know of any argument that says that the philosophy of "the decisive moment" is such that it must be followed.
What the thesis amounts to is a mid-level theory about engagement with the world, the moment of commitment to action, the explanation of the action, and how that influences the aesthetic interpretation of the product of that action. This is topic-neutral. It applies to doing any of a wide range of things. And it touches on a number of questions of deep interest in philosophy and psychology.
There are similar theories about playing jazz and the process of extemporaneous compositions. Those theories apply more broadly than in just music.
In both of these areas, there are no explicitly normative claims (i.e., the claim that you "ought" to create art this way). There are lots of good kinds of music that aren't jazz. There are lots of good photographers that don't do photojournalism according to the Magnum school.
But. Of course the psychological and philosophical claims, if they are true at all, are true in general. You don't have to subscribe to theory of gravity, but you will be subject to gravity nevertheless. In that sense, you don't have to subscribe to the philosophy of the decisive moment as a way to create art. But if its philosophical and psychological foundations are true, then everyone is subject to their implications, whether one knows it or not.
One of the things that makes jazz (like photography) great is that we actually discovered a wonderful creative engine that works in the moment. There is considerable gain to be had from exploring and exploiting that process for creative purposes.