What is state? Every local variable is state. I can convert any global variable to a local variable or function argument with trivial changes. Does it mean that every local variable is the real enemy? Only empty program is perfect. But useless.

I'd say that not just state is the real enemy. It's all about life time of a particular bytes. `(x, y) => (x + y)` is a good function. Its state is discarded pretty fast. `(x, y) => (z) => (x + y * z)` probably is a bad function, its state is preserved for a long time. Global variable state is preserved during the whole program run. Database state is preserved during the whole software lifecycle or may be even more.

And that's not even about state is enemy. It's about how much time do you need to design this particular code. When you're thinking about database structure, that's a real deal. Take a lot of time, that's important and decisions will have impact for years or even decades. When you're designing pure function which does not leak any state, you don't need to think at all, just slap something and move on, you can easily replace it later if need arises.

TLDR: prefer state with short life time, be very careful with code that works with long time state.