Because the game isn't built PvP first, nor is it balanced for PvP.

People quickly discover the dominant strategies and keep abusing those with every encounter, completely stealing away the fun from those just casually playing through the game, it's why mods like seamless co-op became a thing.

I've noticed that PvP players never want to fight those better than them or of equal skill, they only want to kill the type of players who simply want to experience the PvE side of the games. They want the easy wins, the high kill counts, it's why Tarkov players currently are crying so much that the PvE mode is taking away their "chaff", so to speak, and they keep dying a lot more in the PvP since they're now actually fighting on equal grounds with other sweats and NEETs, and not against some weekend dads who play only few hours a week.