I don't think that what is being condemned here is flow.
When I used to practice the piano several hours a day I was in flow, but I wasn't running through my pieces. Flow was what made me able to play through the same measure thirty times in succession, stop and think about what I needed to do differently, then play it through thirty more times, without losing my concentration.
This article is focused on practice and growth. There's a distinction between the work required for improvement and the state required for productivity. To me, flow is more about productivity.
When I used to practice the piano several hours a day I was in flow, but I wasn't running through my pieces. Flow was what made me able to play through the same measure thirty times in succession, stop and think about what I needed to do differently, then play it through thirty more times, without losing my concentration.