On chess websites gains and losses swing more extreme until you play enough games to stabilise. It's a modified elo system or elo-adjascent. This way people reach their "true" rating much quicker e.g. a grand master who signs up will reach 2400 over a smaller amount of games than if he could only gain 2 or 3 points for every game. The same goes for the beginner who starts at 1500 but should be 800, he'll reach that quickly and then play against people around his ability.