That's true, but you can do a lot of that once, and then get on with your life, if you build the right structures. I've gotten a huge amount of mileage from consensus to decide where to send reads/writes to, then everyone sends their reads/writes for the same piece of data to the same place; that place does the application logic where it's simple, and sends the result back. If you don't get the result back in time, bubble it up to the end-user application and it may retry or not, depending.

This is built upon a framework of the network is either working or the server team / ops team is paged and will be actively trying to figure it out. It doesn't work nearly as well if you work in an environment where the network is consistently slightly broken.