Although I'm very, very sympathetic to the idea that class hierarchies often cause more pain than they're worth, using JS to make that point is a bad idea.
In most actual OO languages, there is a clearly defined interface between a base class and it's inheritors: eg in c# you have protected (to expose state), abstract to force implementation and virtual to optionally allow implementation. In no way are you forced to expose all internal state (even though people often do).
I think there's a case to be made against class hierarchies, and also against using OO in javascript. But I'm not sure Ragan made either of them well here.
In most actual OO languages, there is a clearly defined interface between a base class and it's inheritors: eg in c# you have protected (to expose state), abstract to force implementation and virtual to optionally allow implementation. In no way are you forced to expose all internal state (even though people often do).
I think there's a case to be made against class hierarchies, and also against using OO in javascript. But I'm not sure Ragan made either of them well here.