Assuming every function is called the same amount of times and carries the same cost it would indeed be silly to cut up a system like that. But in the real worl

Assuming every function is called the same amount of times and carries the same cost it would indeed be silly to cut up a system like that. But in the real world some parts of the system are called more often or carry a high cost of the execution. If you can scale those independently of the rest of the system, that is a definite advantage. For me the antipattern poses itself when the cutting up into microservices is done as a general practice, without a clearly defined goal for each service to need to be separate. (And by the way, i’ve seen a talk before of an application where the entire backend was functions in a function store, exactly as you described. The developer was enthusiastic about that architecture.)