"Made it possible", or "made it look like R"? add() vs. + is just a mild inconvenience IMO compared to the inconvenience of overloading abuse that I normally see ( like sqlalchemy IMO). I'd personally rather know what to expect from an operator.
We could by analogy apply this argument to adding integers and floats together. It's more convenient to use the + operator for that, but someone could argue that an add() function is just a minor inconvenience, so why bother overloading the + operator?
That is until you have to use it hundreds of times.