Similarly, unit test have become accepted practice, and improved overall project quality, even if TDD is uncommon.
Clean Code is, IMO, too extreme in many respects, but it shifted the conversation and conventions in a much-needed direction.
The final point he makes is a major missing piece; using polymorphism and type systems well is difficult and requires up-front thought and design work that many programmers are both unaccustomed to, and uninterested in. So conditionals remain the norm. That is unfortunate, but also predictable.