Other than framing it in the language of React/FRP, is this substantially different from template engines? Templates are functions from parameters to markup/UI;

Other than framing it in the language of React/FRP, is this substantially different from template engines? Templates are functions from parameters to markup/UI; they're just written in (usually custom) markup languages instead of Javascript. If a template isn't a pure function of its parameters, then surely you're doing it wrong? PS: I've used several template engines which have an "inheritance" feature, which might refute my point. I never used such features, as they seemed to be shoehorning cargo cult OOP into situations where it's not appropriate. On the other hand, having one template include another for some sub-component acts exactly like one function calling another.