Frankly I think both reasons given for the supposed greater difficulty of building SPAs are wrong- and that SPAs have been successful exactly because they're mu

Frankly I think both reasons given for the supposed greater difficulty of building SPAs are wrong- and that SPAs have been successful exactly because they're much easier to develop. Additional logic tier: exactly the opposite is true. A SPA allows to get rid (almost) completely of the logic on the server, leaving there only a shallow layer of services. While traditional web applications always had the problem of a complex logic layer on the backend, with in addition the need to manage complicated interactions happening only client side (because even traditional web applications couldn't afford an entire page reload for simple things like reordering a table, displaying an error message, etc.). Part of the logic had to be replicated on both sides, with all the problems that it creates. Data synchronization- again, given the fact that the entire state of the application resides only on the client and is rendered only by the client, data synchronization becomes trivial- it's just a matter of calling some backend service to store or retrieve the full state. In short, the problem with traditional web apps is that they've always had the need to manage a state on the client as well as on the server; and the client's state was lost at every page reload, or either had to be sent to the server with some hack to be restored after the page reload. A nightmare.