Elixir has features called guards which allow you to check for a condition to be true before a function is called(and will match another version of the same function if it is false). This is used as a crude form of type checking.
They were saying guards are a crude form of type-checking, not intrinsically crude.
Really they are a perfectly regular form of type hinting--as is pattern matching in function heads--when being used for no other purpose than to ensure the correct type is passed at runtime.
