We should recognize that OT is simply another step toward Nirvana. The first crack in OOP's foundation is the so-called fragile base class problem . When designing a class hierarchy for a framework, we are actually designing a house of cards. Each interface between a class and its subclasses is a form of coupling. In fact, inheritance is an extreme form of coupling that would make a structured programming whiz shudder with fright.
Inheritance leads to a high degree of coupling within a framework.
This is bad because coupling is the root cause of the ripple effect in software. If coupling is high, a small change in one place can propagate changes throughout a large part of the entire system. In a framework, everything is connected to a few top-level base classes. Everything depends on these fragile base classes, hence the name of the problem. Changes ripple throughout the class hierarchy, leaving one's design in a shambles.