Why are singleton objects more object-oriented?

Question

In Programming in Scala: A Comprehensive Step-by-Step Guide, the author said:

One way in which Scala is more object-oriented than Java is that cla

Answer 1

Hint: it's called object-oriented programming.

Seriously.

Maybe I am missing something fundamentally important, but I don't see what the fuss is all about: objects are more object-oriented than non-objects because they are objects. Does that really need an explanation?

Note: Although it sure sounds that way, I am really not trying to sound smug here. I have looked at all the other answers and I found them terribly confusing. To me, it's kind of obvious that objects and methods are more object-oriented than namespaces and procedures (which is what static "methods" really are) by the very definition of "object-oriented".

An alternative to having singleton objects would be to make classes themselves objects, as e.g. Ruby, Python, Smalltalk, Newspeak do.