Ruby doesn't have functions. It only has methods. That blocks in MRI happen to be implemented without reifying an object is an optimisation. You can only ever obtain a reference to said block by reifying it into a Proc instance.

Letting you obtain some kind of raw reference to a block that isn't a method on an object would make blocks unlike every other value in Ruby.

> I don't see why there is this distinction where lambdas have to be called differently than functions.

Ruby doesn't have functions; things that look like bare (non-method) function calls in other languages are just method calls on self.

So procs/lambdas can't be called the same as, or differently from, functions—they are the closest thing Ruby has to functions to start with.