[onestone]

You are right about that, I admit.

Still, using the same transpiled code both client-side and server-side is suboptimal at least. E.g. if I target Node 7.x on the server, I don't need to transpile async functions for example (and screw stacktraces in the process).

[onestone]

Also, I might still want to do some things differently server-side in getInitialProps(), despite most of the code being shared. For example, clients might access the API through a load-balanced frontend, while on the server I might want to prefer talking to an API process on the same machine. Authentication might also be different. Of course these things (e.g. the API endpoint) shouldn't be hardcoded, but even then you need to get them somewhere, most likely a configuration file or an environment variable. And sharing these details (names of environment variables for example) with the client is not something I particularly like.