Maybe what matters has to do with why write. If so then I would suggest that the next question ought to be whether the "why" involved is a real or fraudulent why. Do you believe that your "why" is important?
George Orwell said in his book, "Why I Write", that to understand a writers motives you need to understand something about the writers early development.
He then added that in every writer, to one degree or another, 4 things were motives for writing. I would suggest that motives must matter a great deal to create action, and so these motives are useful in this blogs efforts to comment on "What Matter".
1. Sheer egoism. This is probably obvious but he also suggested that writers share this with scientists, artists, politicians, lawyers and others.
2. Aesthetic enthusiasm. This has to do with the beauty of the world.
3. Historical impulse. This is the need to let folks know the facts.
4. Political purpose. This, in part, is "the desire to push the world in a certain direction, to alter people's idea of the kind of society that they should strive after".
I don't see anything in any of the 4 that couldn't have the idea of being genuine added to it. If the person is motivated by a sincere desire rather than one intended to deceive, then these all can be answers to the question, "What Matters".