@TheApexLegendNubPeople mainly use sniper rifle as a mid-range shotgun from 100~ meters, mostly thanks to the Sentinel with its charged shot mechanic and the TT with easy and forgiving wide spread - before it was taken away from us. And there is no way you could win against any auto rifle from this range - unless you can magically headshot them 2-3 shot in a row while being shot at and your aim will flick crazy like it's about to crash the dogecoin market
Arena is a whole different META and play style, you either steamroll people with W key or play a war of attrition to burn their resource. Also because Arena playground are much smaller and you have no need to worry about 3rd party, sniper is actually useful in there.
