If you've ever tried to shoot Marines when they're friends, you'll notice a huge difference compared to shooting enemies, because you get no aim assistance. Makes you realize how important aim assistance is.

: I dunno if you can get
: up to the same reproducible freezing shenanigans in latter Halos to test,
: although it makes me wonder if that sort of setup still exists.

I don't know if you can get frozen personnel in any of the other games. And frozen personnel constitute a game flaw after all, so perhaps it was addressed after H1? Well, they switched to a different engine, and perhaps it never had that problem.