You're just too good at Halo! You skew the whole thing!
lol not what I'm saying and you know it nerd...
You take the DMR and put it in Valhalla, sit in the middle hill, and you get the same type of dead, no movement gameplay. The issue is partly map design, but it's moreso on the fact it can ping players with such tight accuracy over long range distances. The BR in 2 even with its tight spread didn't have the consistency of taking players out in such a range. Only players standing still could it have that opportunity - the only thing holding back the DMR from doing it more often is bloom.
Your logic is entirely dependent on play style, not weapon. Give me the DMR on Valhalla, with or without bloom, and I'm pushing hard... certainly harder than the top of the hill, because I can better control the spawn, and more quickly effect damage on the new spawn we just forced. It also means I force them to play on my terms and NOT take those pot shots, while maximizing effective damage. With less zoom, or say the H3 BR... the smarter play would have been to passively wait on the other team to attempt to push out of their base. And for the team that is trapped on spawn... that 3x zoom now allows you to make effective first shots for a push out of the trap.
Meh... as I said... it has more to do with the person, than the zoom. It has more to do with a person's way of playing the game. Some people look at Halo as a giant territory to control. We have a map, two opposing teams, and there is a constant ebb and flow of killing in order to take positions. Their goal is to as efficiently as possible put the other person in their spawn and keep them there. Whether that's objective, or slayer... Those people will take a 3x zoom and move just as much as before, if not more, precisely because it allows them to be more efficient in attaining their goal.
In CE there was a 3 shot capable pistol with a ZOOM... perhaps the epitome of what we are talking about here... and in general people did not camp. They moved because they felt empowered to move and be dangerous from any distance great or small.