Yeah, I think Ruby represents the end of the line for the one of the main ideas of Smalltalk: that everything should be the same thing. Classes are objects, objects are hashes, have fun. The problem is that programming is primarily about making distinctions. This is a user, that is a product, and they are not the same thing. When everything becomes an undifferentiated soup it's hard for the programmer to figure out what's going on, which leads to bugs, and it's similaryly hard for the runtime to figure out what's going on, which leads to slow code.

More modern approaches have clearer boundaries between different systems. E.g. compile-time metaprogramming has much more structure than Ruby's runtime metaprogramming.