To me, the core of this entire issue is complexity and where it belongs.
My view is that you should perform as much processing as possible in the backend. This allows you to send as little data as possible over the network and allows your application code to make more sense because all your domain logic is centered in one self-contained app.
Now this self-contained app is just a software library, it doesn't do anything on it's own. But you can throw a CLI on top of it and use it through the terminal. You put a web api on top of it and use it from an SPA. You can use it as a backend for a server side rendered app.
The ideal, in my eyes, is that th frontend only concerns itself with actually displaying things. It doesn't get a big list of data, filter and transform the data, then display it. It asks the backend for exactly what it needs and the backend provides exactly what it needs and it displays it and that's the end of it.
Now you can have a website and a mobile app that are both trivial to develop and both use the same backend - if you fix a bug in the backend you've fixed it on both frontends.
I realize this may not always be possible or practical, but I think it is both of those things more often than not.
My view is that you should perform as much processing as possible in the backend. This allows you to send as little data as possible over the network and allows your application code to make more sense because all your domain logic is centered in one self-contained app.
Now this self-contained app is just a software library, it doesn't do anything on it's own. But you can throw a CLI on top of it and use it through the terminal. You put a web api on top of it and use it from an SPA. You can use it as a backend for a server side rendered app.
The ideal, in my eyes, is that th frontend only concerns itself with actually displaying things. It doesn't get a big list of data, filter and transform the data, then display it. It asks the backend for exactly what it needs and the backend provides exactly what it needs and it displays it and that's the end of it.
Now you can have a website and a mobile app that are both trivial to develop and both use the same backend - if you fix a bug in the backend you've fixed it on both frontends.
I realize this may not always be possible or practical, but I think it is both of those things more often than not.