The fundamentals of D4 prevent build diversity

  1. Class-restricted gear. For example, you can’t use ranged weapons on any class that’s not a rogue.
  2. Class-restricted aspects and uniques.
  3. No way to access abilities and passives from other classes.

All of these things were possible in D2 by the way, more than 20 years ago. In fact, a popular build in D2 was the werebear sorceress, which is something that is simply impossible in D4 given the current design paradigm.