Powerful sith (definitely Darth Sidious) need to have a new ability, force scream. Idc how or what it does, but its showcased in the movies and shows. Not to mention the books and lore. That is all
Darth Vader, Darth Maul, Darth Malak, Darth Traya, Darth Nihilus, Darth Malgus and even General Skywalker would make sense but when did Darth Sidious do it?