Combat sports undoubtedly benefit from having weight classes. In a world where all fights were open weight, most of the top two hundred fighters in the world would be the kind of sloppy sluggers who are currently floundering in the lower heavyweight and light heavyweight rankings. Yet few other sports will make the same concessions to the smaller men on the field.
Alexander Volkanovski spent his youth playing rugby at a diminutive five-foot-six and having to stand up to the physical force of men who would be two or three weightclasses above him in mixed martial arts.
https://www.fightprimer.com/advanced-striking-20-alexander-volkanovski-inside-low-kick-footsie