I don't think that's quite correct. I think the authors fully acknowledge that the business case for local-first is not complexly solved and is a closely related problem. These issues need both a business and technical solution, and the paper proposes a set of characteristics of what a solution could look like.
It's also incorrect to suggest that local-first is an argument for decentralisation - Martin Kleppmann has explicitly stated that he doesn't think decentralised tech solves these issues in a way that could become mass market. He is a proponent of centralised standardised sync engines that enable the ideals of local-first. See his talk from Local-first conf last year: https://youtu.be/NMq0vncHJvU?si=ilsQqIAncq0sBW95