On OOP, you create and work with an instance of an object. If you need to work with the instance of the object it makes complete sense that you would pass a reference to that 1 true instance of that object to a different scope.
If you pass an object by value what you are doing is creating another copy of that instance that is seperate from the original instance. So if you work with a copy, then you need to sync up those copies at some point or some other such extra work.
C++ makes you pass in the value of the reference to that object (because everything is pass by value), which is extra syntax. However, when it comes to objects you will always want to be working with the instances you create, so most of the time (if you are doing it correctly) you are using extra syntax to properley work with an object.
While I never pass the value of objects because its just bad OOP, it might be needed in some weird case so it sould be accounted for and that should require the extra syntax.
I think its just the poor implementation in FORTRAN. Modern OOP languages that have a distinction between value and reference variables make working with OOP more effective than C++.
C++ is an extention to C to accomodate many different programming models, so I understand why this can't be. But C++ would be a good language if they ditched the reliance on C and went full OOP (as C++'s most popular use is OOP).
MS did this with C#. So if someone wants to lear a C syntax language that is truley OOP then they should go with C#. Also C# is great because of the way it implements templates. C++ is still better than Java at runtime with templates but its still lacking as its just a macro basically. (and don't go on a trip about how C# is locked in to Windows and the desktop because it really isn't).