That's even more work? Most developers already have redis/Postgres running, the issue there is the added complexity in complex operations.
Not to mention, microservices are not always the answer. And even if they were, they're still an insane amount of more work than literally changing what functions you call.
I'm not saying you should never use an RPC, but I've significantly reduced the times I'd want to use one. The only reason I even advocate for one now, is because I prefer to empower developers to use whatever language makes them happy, even if I personally greatly prefer Elixir.