I agree that there things work differently on the server and on the client but the lines are getting blurred. For example, you might not need api versioning if

I agree that there things work differently on the server and on the client but the lines are getting blurred. For example, you might not need api versioning if you only write a SPA application, there is usually some caching on the client also and it seems to increase, the concurrency problems are starting to show up in the clients (promises and callback hell) and sometimes you want to duplicate a lot of the security things to the client to give faster feedback and a more dynamic gui. Database queries are probably mostly done on the backend but there might be queries in some rest format in the client that are sent to the server and there might be IndexedDb queries instead.