It's the job of the code editor to get that information surfaced to me at the proper place (e.g virtual content like vim inlay hints, hover tooltips, those vscode embeds or whatever they are called). If I need to jump quickly I have projections† set up.
Having the types inline isn't that useful anyway as it gives yo only the signature but gives you no info of whatever type intermediate things are without much thinking.
And interesting things happen when you have separate `.rbs` files: I started to develop some things type first then progressively fill the implementation in.
RBS is a thing; we use it extensively.
> Good luck finding where the `process` function is called from
I don't use it like that but I seem to recall RBS itself has a query mechanism and can answer these kind of questions.