"Object-oriented" was like "agile" in the late 80s and early 90s. It was viewed by management as a quasi-silver-bullet that would solve the software complexity crisis -- and by consultants as easy money. The qualities of Smalltalk that were selected for in the object-oriented craze were the ones that most appealed to computer-unsavvy middle management -- the ones that helped them herd programmers by the dozens or hundreds without them stepping on one another's toes. So classes, data encapsulation, inheritance, and virtual-method polymorphism were emphasized to promote the creation of sealed components that could be extended or wrapped but not changed (Brad Cox's software IC dream) and late-bound messaging de-emphasized in order to enforce static typing constraints.