If you declare message passing as the only true form of OO then you're just drawing your box too big. Within the infrastructure that allows you to pass those me

If you declare message passing as the only true form of OO then you're just drawing your box too big. Within the infrastructure that allows you to pass those messages around are many interesting lower-level problems that require the uglier, statically typed and binary-incompatible OO programming maybe better described as class based programming.