It is advised not to use the message isKindOf: in applications.

I do understand that it is not a good idea to do different operations depending on the kind of an object in one method. But in my (Javascript) production code I do a lot of checking if an argument to a function is "instanceof" someObject. When it is not the expected type of object, an exception is thrown. I do this to ensure that someone (=another developer) does not by accident passes a wrong type into my method.

Reading this, I realized, that I never saw such type-checking in Pharo production code.