> Closures in particular are a very powerful tool in async/multi-threaded environments, but in the stateless/sync environment of a web application environment, they collapse down to syntactical sugar, and solve nothing that cannot be solved in other ways.

Every feature in every language is syntactic sugar for ASM instructions and solves nothing that cannot be solved with raw machine code. It's precisely the expressiveness of the higher-level features that gives them their power.