I'm pretty sure most people who strongly like OOP are sure their particular definition is the correct one. I haven't seen many people agree about what that definition is though. I generally dislike OOP, but perhaps that's because my definition is "encourages implementation inheritance". As you're keen to note, the standard list of other things (encapsulation, message passing, dynamic dispatch, interface inheritance, and even "establishing protocols") are available in a lot of other languages which people don't generally consider OO.
Perhaps I'm ignorant, but I like my way of doing things, and a.f() is less attractive to me than f(a) for all the reasons I listed.
I'm pretty sure most people who strongly like OOP are sure their particular definition is the correct one. I haven't seen many people agree about what that definition is though. I generally dislike OOP, but perhaps that's because my definition is "encourages implementation inheritance". As you're keen to note, the standard list of other things (encapsulation, message passing, dynamic dispatch, interface inheritance, and even "establishing protocols") are available in a lot of other languages which people don't generally consider OO.
Perhaps I'm ignorant, but I like my way of doing things, and a.f() is less attractive to me than f(a) for all the reasons I listed.