As a mainly backend developer who dabbles in front end, there seems to be a lot of overlap between these JS framewors and backend frameworks. You are likely going to need a backend framework to serve JSON and do data validation and authentication, so I don't see the need for having so much functionality on the frontend frameworks. The View part seems to be the part I need. It gets really confusing as to where the logic should end up going (and a lot of it seems to make more sense on the back end anyway - why do I need routing in the front end for example?).