Because players tend to choose the path of least resistance when they play games. They opt for whatever fit/weapon will give them the most kills for the least amount of effort. Assault rifles are pretty easy to use and many people spec into them early on because it is a very recognizable weapon.

Also, "The best defense in not a good offense, it's a good defense." I see you there Marcus Kincaid.

The reason why people don't use niche weapons is because they want no downside. The assault rifle has 0 downsides. It is also just as good as most niche weapons in their own niche, why use something else?

Why do people keep asking for everyone to use some niche weapon, or do you want some "shotty sniper get gud scrubz" Halo game play?

My main character thrives on niche weapons.

My favorites are the MD, LR, SG, and SL.

But I also use Burst and Tactical ARs; do those count as niche weapons?

Theres too many who want to win just a bit too much probably, the most hilarious is playing a pub match and the other team caps everything super quick like it matters, the reality is that the shorter the match the less sp and isk we get.

The Breach AR is not a niche weapon, but I do believe that the SMG is a very niche weapon. If you want to be effective you have to get within 20m of the target.

I just wish the Regular AR was not so ridiculously OP right now. It's existence really makes me embarrassed to have the SP into ARs. Even if I don't use the vanilla just seeing one is like watching a video of squads spamming Assault MDs on a high tower or building.

Sickening.

The option should be there but they shouldnt be forced into it though
And lets all just be completely honest for a minute and admit the AR really isnt over powered but that style of weapon is generally used by guys with a lot of modern FPS experience rather than older games were almost everything was niche and due to that things like mobility and attack angles are more important that what you are using and that alone can trump the rock paper scissors system a lot of people think that this game should run on and not what it actually does

I mean hell, I can be just as effective with the SMG as I am with an AR and its partly because I dont have any notion of X should beat Y should be Z and stay on my toes all the time

Not just those two but grab a list of FPS games and see how many have a general purpose weapon with no downside or particular strength but that lack of a downside being its strength and at least get COD mechanics right if you want to harp on them since the perk and fitting systems there are really just a more condensed version of what we have here
Im no fan of the series since its just yearly full priced map packs but I do like to know about something before whining about it

And it really really isnt OP, widely used sure but not OP
I mean if your metric for OP is something that kills you often then scrambler rifles are OP to me since I get killed by those most often or if you want to break it down with some actual reasons the scrambler rifle has a greater range, more damage, and has the same ROF and lack of kick as the old tactical AR which people screamed was OP all the time

*Note to you guys already getting your panties in a twist because OP was close to the words scrambler rifle, I dont think its OP I think its fine

I use a MD, flaylock, shotty , smg, and Nova knives and out of them only the last three are not outperformed by a rifle in their roles and only slightly.