been playing alot of B2B multiplayer (back to basics) were the only main weapon allowed is bolt action rifles with iron sights but too often im killed across the map miles away were
A: i cant see them
B: how are they hitting shots that long with no scope
C: even if they have been spotted, trying to hit a shot that far away is just too hard
trying to hit like 2 pixels from miles away with awful iron sights and constant weapon movement just seems way too hard but these people are able to effortlessly pull it off. not to mention the constant explosions, dust, smoke, fire that gets in the way but yet they can see right through it all like its not there and blast me.
is this just a case of the players who still play this are mega sweatlords who have mastered it or am i missing something?

It's a skill that many Scouts have.
Don't forget that if YOU can spot your enemies, then THEY can spot you as well. And you can stay spotted for couple of seconds, even with walls of smokes, they can see the red dot on you. And then they can occasionally hit or kill you, just cuz they knew your location because you were spotted.
Not everyone need scopes to snipe perfectly, if someone has Mastered the Bullet drop mechanic, then they can calculate the shot even without a scope. The more you try to use Iron sighted Snipers, the more you'll understand this.
To avoid getting killed like this, don't roam in Open fields, and play cover to cover, stay in covers so you don't always stay spotted.
Hope that helps ✌️

Yup, bullet drop mastering is a thing. All great Scout players use it, because Iron sights don't give your position away.