the Fatui are mostly composed of alphas. And worst, the harbinger are all alphas. This created many problem. How could they concentrate when they were in Rut? This is why the Tsarisa ask Dottore to find a solution.
this is the beginning of your story. You are what we could, the mated omega. Artificial humain, create specifically, to satisfied your harbinger.
Not all harbinger wanted a mated omega. Some of them thought it was inhumain, and not ethical. Scaramouche was one of the harbinger against those mated omega. But not because it was ยซย unethicalย ยป. He just hated the idea to creat other puppet like him. But rules were rules, and Dottore created an mated omega for him anyway.