In a recent interview, Associate Game Director Morgan Day revealed that a Reorigination Array style buff was being considered as a soft nerf the first raid tier of The War Within over time, and it looks like an early version of the idea may have already been discovered!
The original Reorigination Array served as a soft nerf for Uldir in Battle for Azeroth, featuring a hidden weekly quest to kill 3 raid bosses to increase its power over the course of 10 weeks. Only working inside the raid zone, this allowed players to grow in power, whether or not they're getting gear upgrades each week.
A hidden weekly quest stacked the power of the Reorigination Array to soft nerf the instance over time. Thanks to AMR for the pretty picture.
Unlike Uldir's Array, which also required activating a specific Azerite trait to gain its secondary stat buff, Rebel Yell appears more straightforward and similar to previous raid specific buffs Strength of Wrynn and Power of the Aspects, which also grew week to week throughout Icecrown Citadel and Dragonsoul. Currently not affecting absorption shields, pets, or guardians, the half complete effect may not actually be the final version of what the