^^^^^^^^^^^^^
And how that would affect the integrity of the game ??
343’s answer is that the game doesn’t have access to enough memory (not hard drive space but probably RAM) to load additional assets (ie. DLC) on top of what’s already there for SOPS. However that is a proximate, not an ultimate, cause. The ultimate may have something to do with the competence and efficiency of those who built the core engine SOPS uses (probably bungie) since as far as I can tell Halo is the only game still trying to get around these sorts of very basic DLC issues.
Spartan ops.
I don’t recall that explanation… PVE content generally is a different thing to PVP. Remember firefight and how they couldn’t just add friendly AIs to existing maps. They didn’t want to break things by trying to add extra stuff I believe.