We have to think about why this language is even worth mentioning today (partly I think by comparison ...)
I "secretly" think that Self would have achieved that too (and even better because is not constrained to the artificial abstraction of classes) but it never had a chance due to its unsuccessful IDE.
Our cognitive system converges too much to objectify things to ignore. We compulsively do that. There is something about objects that fits our cognitive system better. It's a waste if we don't take full advantage of it.
Maybe also easier to match to hardware than LISP or FP DSL's along lines of Haskell. I'm a little out of my depth there, though. I just remember LISP machine and OS crowd having to innovate hard to fight performance issues. PreScheme & T being exceptions where low-level was easy.