Fully agreed. But how many Java/C++ programmers doing "OOP" would you guess are familiar with Smalltalk and Self? I'm not talking about people interested in PL theory, but the thousands of programmers out there working for the maintream industry and "doing OOP".
I'm going to guess: not many.
Lest I seem dismissive or condescending: I shamefully count myself among those industry programmers. I'm not at all familiar with Self, and my only knowledge of Smalltalk comes from one CompSci course and a presentation at OOPSLA.
Recently I was making a case to coworkers that the typeclass pattern in Scala (and presumably typeclasses in Haskell, I'm not personally familiar) was a completely OOP construct in the vein of CLOS/Dylan. I was met with raised eyebrows all around, and some of the people in the room were pretty far beyond "those industry programmers" so the problem isn't just one of naiveté
"Smalltalk and Self" more dramatically illustrates why its disturbing (to people familiar with the history of OOP), but what applies to them also applies to their more-currently-popular descendants, Ruby and JavaScript (among others).
Any definition of "Object Oriented Programming Language" which excludes Smalltalk and Self is...disturbing.