It seems to work reasonably well for the two non-toy apps I've worked on that use a single state object. There are two key rules required to make this work, how

It seems to work reasonably well for the two non-toy apps I've worked on that use a single state object. There are two key rules required to make this work, however: 1. For each domain, state can be modified in one place (in React, a store). 2. For each domain, state can be read in once place (a Presenter). This preserves data-hiding for the most part, and keeps you from having to play hunt-the-wumpus when you need to change the data structure.