Id argue its because of the source engine and its weapons being hitscan, they couldnt accurately control how the projectiles fly so they couldnt make accurate damage numbers, it would have to have a hefty dropoff quickly to an unreasonable degree or feel overpowered. Not only that, but you didnt get flettchets, only slugs as an alternate choice and if youre only gonna use slugs you might as well use a gun with AP ammo instead, since normal shot is awful against armor even in sandstorm.
I think the projectile system makes shotguns able to be more realistic because as much as youd like to think it cant, they really can shoot pretty far and be effective, but even if you get killed by a shotgun nearly accross the map, theres no question a rifle wouldve been more effective and less RNG.
With long range shotgun shots, sometimes itll take me 4 shots to kill and sometimes it takes 1. Its pretty much down to spread assuming I aim properly and some hit the head.
Funny but i dont remember being shotgun sniped across the maps in Source very often, maybe its cos i only played for 800 hours or so
I think shotgun was way weaker than it is now, and basically every other weapon was way stronger than it is now. I don't think I've ever survived a shot by a shotgun, while I regularly survive one or two hits from assault rifles. It feels ridiculously unbalanced to me at the moment. I'd say shotgun needs a supply cost increase and a range nerf because one hit kill AND being easier to hit something with it is a weird combination. I once even got two kills with one blast from the shotgun, I wish all guns were this powerful (like they used to).