The problem they were trying to solve was multiple inheritance, and by nominal type not by code reuse. So interfaces, basically.

So these guys essentially assigned a hashcode to every function of every interface and then you would do dispatch instead of obj.vtable[12] you would do modular math x = singature.hash % len(obj.vtable) and call that.

I believe this was sometime around 2005-2008 and they found that it was fast enough on hardware of that era to be usable.