That’s news to me. As far as I’m aware there’s really no reason to believe that rifles come with scopes. Obviously the sniper conversion kit adds one, but prior to that I’m skeptical. In any case, that doesn’t mean that scopes couldn’t be added with their own special mechanics.
As for the stuff on maximum ranges vs viewing distance, I agree that the guns are arbitrarily limited in their range based on the viewing distance. That was one of the purposes of coming up with the scope/tunnel-vision idea. You could dramatically increase your view distance by drawing a long rectangular view using the same number of tiles, just oriented directly in front of the player character. You couldn’t see as far to the left or right, and you couldn’t see behind you, but all of those blacked out tiles could be used to extend the view for the purpose of long-range shooting. You should be able to get about 2x the viewing distance in one direction by sacrificing tile visibility behind you and on the sides of your line of sight. So range could become a bit more of a factor, though even in that case I’m doubtful that the distance would be enough to represent the maximum ranges of rifles.
It’s hard to say how difficult/feasible it would be to change the way the game draws its tiles, though.
Yes, I really can’t stress this enough. People seem to be treating sniper rifles like they are some special, unique breed that require their own special mechanics. While there are some purpose-built sniper rifles on the market, they are mostly masturbatory weapons designed for public consumption, and aren’t really superior to a Remington model 700P in any meaningful way. The only significant difference between the 700 and 700P is the barrel. And that is the rifle used by the armed forces and police forces in the US and (I believe) a good part of the western world. And they actually use their rifles for the task that sniper rifles are famed for. These other purpose-built sniper rifles are rarely ever used by actual trained snipers, as far as I am aware. What they are is expensive rifles designed to look intimidating and a lot of little tweaks to improve firing comfort.
Any new mechanics should be applicable to all guns; or where it makes sense, any gun that can mount a scope.