Do people honestly think other languages don't do whatever definition OOP has today? Encapsulation & polymorphism? Message-passing & late-binding?
Inheritance is the one thing that the other languages took a look at and said 'nope' to.
(Also, the OOP texts say to prefer composition anyway)
It is very difficult to tell whether this is a definitional problem - people believe any kind of encapsulation is OOP - or if some people can't wrap their heads around how to do encapsulation without message passing and the rest.
What they don’t get with protocols, though, is polymorphism. I think a lot of folks confuse them.
I wrote about an odd bug that I encountered, from protocol defaults: https://littlegreenviper.com/the-curious-case-of-the-protoco...