I’m gonna have to stop you right there.
There’s no “supposed” in the Halo world. It’s all a moving target. Shit changes depending on whose in charge. Spartan IIIs were supposed to be the much weaker and cheaper solution to the Spartan IIs with low priorities, and here we have a whole team of them wearing Mark V armor and one of them could even fly a top secret spacecraft. Brutes were supposed to be big lumbering powerful bullet sponges with heavy use of sadistic torture and brutality on the field, and from Halo 3+ they just sorta floated from situation to situation completely mellow and damn near harmless. Especially in reach.
I mean Halo’s no MGS in terms of inconsistencies, but between a complete re purposing of a class and the addition of a pelican throat pouch and a lower jaw, the latter is much less severe.