My first answer is that one of the most amazing mechanics ever designed is health points, I believe invented by Dungeons and Dragons. Almost every non-health win condition feels more arbitrary than health. Whether it's shooting balls in hoops, crossing a finish line first, or collecting victory points they are all less intuitive and feel more contrived than "you have this many points, at 0 you die."
The second is that many game designs are essentially about conflict, whether with other players or game agents. The ultimate conflict is life or death violence, aka combat. So it's a quicky and easy way to raise the metaphorical stakes. If you take an olympic fencing game and instead make them use real swords and no armor then it's a lot more dramatic with no change in the game mechanics.
Making non-violent games is not undesirable, it's just harder to do well when combat fits so naturally. You end with non-violent games being worse on average, non-dramatic low stakes metaphors and contrived win conditions.