It's arguably faster and of more benefit to learn OO in an OO language, and then work backwards to figure out ways to implement those strategies in C (eg. polymorphism using structs with arrays of function pointers, or win32 send_message constructs).

It's similar with functional programming. Figuring out folds, pattern matching and monads is probably easiest in haskell or Ocaml/F#. The decision to apply those techniques in other languages without native support then becomes a judgement about the benefit.