I'm not commenting on the realism of the zoom system, but the consequences it has to the gameplay are set in stone like Newtonian physics.
What consequences? If they were so set in stone, surely you'd be able to specify them, which you didn't.
For one, it's not like it devalues the sniper class, since scopes' magnification power should be based on the distance FOV, not the peripheral FOV. In other words, a 6x scope with magnification based on a 90 degree fov would yield a 15 degree fov...which would only be twice the magnification of your distance vision fov (30). Thus, a 6x scope should yield an fov of 5, or else it's only giving you twice the power of your zoom view, simulating a 2x scope. I'm not sure what RO2's scope magnifications are based on, but that's a potential issue.
For another, if distance fov were properly implemented, there would be key gameplay differences from a scope - distance vision should be instantaneous, rather than forcing you to stand still and hold a key. A scope lense and scope tube shouldn't be rendered around the screen to further block your peripherals. Really rather than being switched on and off by holding a key, your fov should be adjustable incrementally via the mousewheel - turn it from 90 to 80, 70, 60, 50, 40, 30, up and down wherever you want it at any time, and leave it there while you run around and do your thing.
If everyone can zoom, it can't be called unfair. If you die because you were zoomed in too far to see someone flanking you, or because you chose not to zoom, it's your own dumb fault.
Lastly, there are gameplay disadvantages to a fixed fov as well - SMG's are upgraded to Assault Rifle status since no one can spot targets past their maximum range. Hence, people complain about how easy it is to snipe with SMG's at 200-300 meters when the actual distance is only 50-100, and since there are few viable ranges where rifles actually beat them out, SMG's get artificially nerfed in damage and recoil in a weak attempt to compensate.