Which is really sad because "hard" difficulties in most games just mean that you have less health and NPCs do more damage or their "cheat factors" are turned to 11. They're still the same stupid NPCs as on "easy", but now they just headshot you behind cover and have zero recoil / perfect accuracy. It's technically difficult but not really fun.
One of the most obvious examples of this is GTA 5 where all NPCs are equally dumb, but "harder NPCs" just mean that they tank huge amounts of damage, while they have very little aim delay and essentially perfect accuracy. Due to various bugs in the game they'll often shoot through walls or even entire buildings: technically hard, but not fun.