Zeroing isn’t a magic wand. You have to hold the key about 0.5 s, and it only really matters past roughly 100–200 m. At around 300 m the round still gets there in about 0.5 s; at around 800 m it is about 1–2 s. Breath-hold also matters: steadying the scope adds about 1 s of transition; ADS to zeroing to breath is not instant.
From the target’s point of view you see a bright glint and a tracer-like fireball coming in, often visible even in shade and even if the head is not facing the scope, so a small strafe can be enough to survive. Bipod is not a free aimbot either; there are elevation and traverse limits, and if you need more angle you must tweak legs or micro-reposition, which costs around 0.5–1.0 s. Add it up: zeroing plus breath or transition plus flight time usually leaves the target about 1–1.5 s to react, and in worse cases up to 3–4 s. It is not free kills; it is timing and positioning. Proper sniping also means relocating. If you farm ten players from the same perch, the lobby learns the line and you get pre-aimed or mortared off that spot.
If zeroing is going to be removed, the sniper round's tank-shell-like glow should be fixed too, or add a no-tracer ammo type. Also, in real life ghillie suits act as thermal concealers, so ghillies shouldn't be visible to thermal cameras either. So if you want a level of "realism" that removes zeroing, I'd also expect tracer glow to be gone and ghillies not to show up on thermal. And a bullet at 800 m doesn't make that huge of an arc; it should travel faster.