In the anime, Kaiba fires them as they offer a peace offering in the form of a virtual reality game
At the start of the game, players draw their hands and place a basic Pokmon card into their active slot, before placing any additional basic Pokmon cards onto their bench
Giving every opposing creature -2/-2 on the way in and from now on is basically unbeatable for an awful lot of decks, and thats not even factoring in the ridiculous +2/+2 to your team
It can also be a nod to some fairy tales
Following the Series 1 template, each card places its starter inside a scene built from that regions most recognizable landmarks, items, and iconography, so the cards read like snapshots from a Trainers journey rather than studio portraits
Exhaust abilities arent limited to putting +1/+1 counters on creatures, but most do it as a physical reminder that the exhaust ability has been used