> 3. The object model available in Common Lisp was more powerful than languages like Java/C++ because it had to fit into Lisp terms (“the art of the metaobject protocol” was the 1991 book that explained the more powerful substructure lurking underneath this object system), so a CL programmer could maybe use it to write a quick sort of aspect-oriented programming that would match your needs.

In addition to that, Lisps are sufficiently flexible that before CLOS itself was developed people were extending Lisp in Lisp to try out different object oriented models that fed into what became CLOS. That's hard to accomplish in most other languages, if it's even possible without going to a third party tool or digging into the compiler itself.