I was thinking about react + flux, eg this line from the flux overview [https://facebook.github.io/flux/docs/overview.html]: "This structure allows us to reason easily about our application in a way that is reminiscent of functional reactive programming, or more specifically data-flow programming or flow-based programming, where data flows through the application in a single direction — there are no two-way bindings"

Anyway, I imagine people refer to react as "functional" because they conflate "declarative programming" with "functional programming."