There are two really important factors that make peeking very strong in Tarkov, entirely aside from lag (what many Tarkov players call "desync"). The two factors are
- The tightness of hipfire groupings
Have a look at these two images. They are pictures of hipfire groupings for the mostly stock M4 in Tarkov and the latest Call of Duty at approximately the same distance from the target surface. Notice how much more spread there is on the Call of Duty groupings. Motion absolutely kills hipfire accuracy in most shooters. You have to get very lucky to kill anything with hipfire with spreads like this. This effect would be even further exaggerated in games like Valorant and CS:GO.
Note that in both cases we are not using a targeting laser. I know that hipfire spreads are even tighter in Tarkov with a targeting laser.
- The damage potential of headshots
Any player not wearing a face shield will die to a single face-shot from almost any ammunition. With many ammo+face shield combos, even the shield will not prevent a one-hit kill. Contrast this with most other shooters where headshots with automatic weapons have artificially capped damage, and generally do not give a one-hit kill.
The combination of the extremely tight hipfire grouping and the damage potential of headshots in this game makes prefiring at head height and strafing the path of your gun across an area where you know an enemy will be very strong tactics for getting kills in this game.
How To Fix
This issue would be somewhat ameliorated by modeling the brain case and spinal column, and reducing headshot damage for shots that don't pass through those hitboxes. So a shot that grazes the cheek would generally not be a one-hit kill. I don't know if this is the best idea, but it might help with this issue.