You can have a single shot, more precise weapon without doubling the range.
I mean, if you put the DMR on Standoff, the game will play objectively worse. Whereas you could use the open silo areas off to the sides because of how the BR limited range, with the DMR they would become no mans lands; anyone down there would get eviscerated. Likewise, players atop a base could destroy guys walking out the front door of theirs. Infantry routes dry up, map movement comes to a halt, players turtle up, and you get what Devolution has been trying to describe to you. That would happen on every single BTB map in the course of the Halo series. It unquestionably reduces the importance of a number of key variables in the sandbox, reduces the number of combat situations, chokes off how dynamic the game plays.
This isn't even up for debate. It's like arguing that a game of snipers does not discourage players from using open spaces. Um, it sort of does. And likewise, the DMR chokes off what used to be perfectly usable play spaces, sight lines and tactics. Some things are a matter of opinion, but this really isn't. It's a simple cause-effect relationship. Longer range combat restricts how versatile a map plays, full stop. You may like that, which is fine. But the effects described are absolutely what has happened to Reach.