It's to keep design space open and to minimize developer work.

Let's say we decide to keep an overperforming gun. It does all the things. It has all the ammo, all the damage, all fire rate, all the reload speed. Now, all future weapons have to be made with that as a consideration. Why would players choose this new weapon, when there's the old overperformer? The design space is being controlled and minimized by the overperformer. Players will complain if new weapons aren't on the level of the overperformer.

Now, let's say we have ten weapons with one clear overperformer. Now, we can either nerf a single weapon to bring it in line with the others, or buff nine weapons to attempt to bring them up to the level of the overperformer. Assuming the balance adjustments of each weapon are the same amount of work, that's 9x the effort. However, if we assume we do this extra work to satisfy players, now we have ten overperforming guns and players find the game too easy, so now we also have to buff enemies to match. However, the game isn't designed to handle these increase in difficulty. Players complain if we just add more health to enemies, so we have to do other things like increase enemy count, but adding more enemies increases performance issues. It's a cascading problem.

I consider nerfs a necessary evil. It's absurd to ask developers to always buff weapons and give them so much work when they could be developing actual additions to the game. Sometimes, a weapon really does need a nerf.

Making all the weapons overpowered to match ruins the intended difficulty.

I dont know what everyone is so upset about, the shotgun feels fine, the recoil doesnt feel bad, and the mag size isnt a huge problem for me.

Plus the flamethrower buff and laser cannon buff are super nice. Im usually in favor of the whole "buff everything else, no debuff" but this honestly feels fine.

Did you ever played Payday 2, where powercreep made us go from guns with all the best attachments could maybe kill the toughest enemy in the game in half a mag, or about 15 shots, to the devs needing to implement 3 (technically 4) more difficulty levels with new enemies that were just old enemies with more resistances or 10 times the health as their stock launch counterparts, and those things dying in 2 hits from all the meta build weapons. All because they kept introducing more powerful weapons, more attachments that made launch guns more and more obsolete, and general more power creep through skill tree expansions and entirely new jobs for perks. The player counts for that game dove off a cliff after players realized each DLC was just pay 2 win garbage and even using stuff you could get only from the base game and free updates left every weapon feeling samey with the same tactics being used and things not in the meta utterly ignored by anyone playing end game content. Because instead of reigning in the things that overperformed and broke the balance curve, they just kept powercreeping new items into the game.

This game has like ten difficulty modes.

I’ve been playing since launch. I played a lot last night. I do not see the problems. I play on hard difficulty. I have a good time whether winning or losing.

There are players that take the game far more seriously than I and honestly they make the game more tense than it needs to be. They make it feel competitive, in that if I’m not doing what they think a “good” player should then I’m unwelcome.

I think the vast majority of complaints stem from these players. I lament that another Call of Duty is not coming out sooner so that the community can diminish into relative obscurity, hopefully populated with like minds that view this as a game and not an e-Sport.