This may not answer your question and may not be 100% correct.
Message passing means that objects have their own data and do not have shared access to it. This makes multi-threading and parallelized code very easy to do because you don't have to worry about data changing unexpectedly. Clojure, and other languages, achieve this by making data immutable, which has a similar effect.
As you mentioned, after Alan Kay used the term "object-oriented" to describe Smalltalk, people focused on the objects instead of the messages and created languages designed around the idea of being object-oriented instead of around message passing (I believe Objective-C and Ruby do message passing), thereby missing the benefit. All OOPLs not based on message passing should die.
Also, unlike Java, Smalltalk has no classes. Any existing object can be used as a template to create a new object.
Message passing means that objects have their own data and do not have shared access to it. This makes multi-threading and parallelized code very easy to do because you don't have to worry about data changing unexpectedly. Clojure, and other languages, achieve this by making data immutable, which has a similar effect.
As you mentioned, after Alan Kay used the term "object-oriented" to describe Smalltalk, people focused on the objects instead of the messages and created languages designed around the idea of being object-oriented instead of around message passing (I believe Objective-C and Ruby do message passing), thereby missing the benefit. All OOPLs not based on message passing should die.
Also, unlike Java, Smalltalk has no classes. Any existing object can be used as a template to create a new object.