To answer the headline: Functional languages are as useful in pretty much any context non-functional ones are, they just need to be handled a little different.
Functional languages’ goal tend to lean towards static or predictable typing and reduction of clandestine mutable state changes. State has to change in a program, it’s just about how its handled, and this is more about reducing referential update behavior.
Like in Python, you can have a list, pass that to a function that returns None, but deep inside that function appends to the list, and you may be surprised that your list is different as a result. This would (typically) not happen in an FP language, you would have to explicitly return the changed list up the stack of functions, and as a dev you could see from a glance that the list could change as a result of the function, leading to less surprises.
“IO” is of course an outlier, as it’s leaving the safety bubble the language provided. I could read the same database row twice in 60 seconds and get a different result, because someone else could make a transaction in that time. But once I have read the row and parsed it into a data-model, I can expect that my model in-code won’t change unless I tell it to.
No he did say in a public update video that he did get Hochul to give NYC more from the state’s budget. Not like “this fixed everything” kind of money, but some of it was from the State.
And I mean, sure probably from State taxes and all, yea, but that’s just how governments work