So let’s answer the code structure question first, don’t use the one in this example it’s just meant to be used for an introduction.
Now onto the Redux UI State and Meteor data state. The reason you still use both is because Meteor relies heavily on pub sub. Atleast that’s how most build apps. The alternative being Meteor methods. So instead of introducing a whole new concept to manage reactivity with the server, it’s best to let Meteor handle the server data. Soon, this system will be replaced with reactive graphql and in this case you still would want your server data separated from client data. This separation makes for a better Dev experience