I think Blizzard just overdid the whole Warlock remake... They designed all the specs from ground up to be modern.
This means that regardless of what spec you play and what talents you pick and what your reforging is, your DPS is not going to budge that much. There are still theoretical and mathematical best options, but still there is literally NO difference as a Destro Warlock if you go high Haste, Crit or Mastery. Most just go with Mastery as it benefits AoE/Cleave the most. Even Demonology can go with all 3 Secondaries and still perform as if they went with theoretical best.