You say this like bolstering is a challenge, it is not. It literally just slows down the dungeon arbitrarily by forcing you to pull small, and also preventing you from pulling trash with boss, which the latter actually poses a challenge as you need to deal with boss mechanics + the trash you brought it at the same time, rewarding skill and proper cd management with lower time on the key.
Enrage is dispellable by druids, and many other abilities are purgeable/dispellable. It’s just a boring affix that adds no depth to M+, it does the opposite.
You could argue it’s a challenge because you can time every mob to die relatively at the same time, but then you realise this is unrealistic because you’re one corruption proc away from messing up everything, and in a dungeon with bad graveyard updates I.e King’s rest and Shrine of the Storm then it just ruins the whole key.
Certain affixes need to be revamped, such as bolstering. Gladly some work is being done in shadowlands as grievous is now changed, reducing one stack per non periodic heal and bursting is a dispellable affix. Bolstering is another that needs work.