The "status quo" way erodes the benefit of Rust's error system.

The whole point (in my mind at least) of type safe errors is to know in advance all if the failure modes of a function. If you share an error enum across many functions, it no longer serves that purpose, as you have errors that exist in the type but are never returned by the function.

It would be nice if the syntax made it easier though. It's cumbersome to create new enums and implement Error for each of them.