Not sure I understand your scorn.
Big maps, small maps... if I run with my teammates, we can teamshoot. If I don't, we can't.
Even when there ARE 1v1s though (you meet someone from the other team, and nobody but the two of you are around)... you know FROM THE VERY FIRST SHOT what weapon he's using. After that, the difference between a light rifle that was available in a loadout and a light rifle he picked up on the ground is nonexistent.
With all the boltshot griping recently, I've been paying attention to boltshotters more than I did before. (Overheat and I played a game where the entire other team was using them - a first for me. I think I died 3 times to boltshotters - a record for me.) The Boltshot makes a lot of noise when it charges up. I can hear it even over the din of battle - I KNOW someone's gonna come around that corner and try to blast me. So I backpedal. He comes around, I'm out of range, he has two choices: he can fire (and do a little damage, but not enough), or he can switch weapons (giving me time to get shots on him before he shoots me at all).
When I get caught by a boltshotter, it's because I wasn't paying attention to my environment. That's no different than being caught by a DMR guy. Or a Light Rifle guy. Or whatever.
Again - my stats show that barely more than one percent of ALL MY DEATHS come from Boltshots; as an annoyance, it just ain't on my radar.
Now maybe this is all because I suck at Halo, and so the people who are fighting against me (and using Boltshots) suck too - so what I'm seeing and what you're seeing are totally different. But I can't really speak to that; I haven't even seen a ton of boltshotting in videos.
::shrug:: That's my experience, anyway.