Well all PVP multiplayer FPS's don't have any grind. You play to kill your opponents and that's it. One of you wins, one of you dies. Try playing Armed Assault 3 - it has PVE and PVP - do a mission with your freinds, no grind there at all. You either fail the mission or you don't. Try any racing game - there's no grind there as you're racing to win the game. Flight sims are the same - zero grind. Portal has no grind - it's a puzzle game so puzzle games don't grind neither do turret defence games. What about Total War games - are they a grind - nope. Survival games like The Forrest or Subnautica aren't grindy either.
True, but playing the same levels over and over again until you get good... building your experiance and skill is seen by some as a grind and one which some players today actually pay to avoid with the advent of loot boxes with Buffs inside and paying to unlock all weapons and character classes from the get go.
Which is why we keep seeing pay 2 win mechanics becoming more common place. Play to some is grind to others and those that dont want to work towards their goals... complain.