Beards are anti-punch blunt-force shock absorbers with 37% effectiveness.
Fur counters slashing damage first, blunt second, and piercing last. Cuts were deadlier before modern medicine. A beard armors the face and neck against cuts. With sweat lubrication, a beard makes blows slip and deflect rather than landing flush.
The conclusion that beards are evolved by sexual selection for fist-fighting is sound. However, the article focuses overmuch on the modern pugilistic KO, versus the much bloodier bareknuckle boxing. Slashing and sweaty slipping are more relevant than blunt damage via a piston into an anvil.
An ethnicity that lacks beards therefore did not evolve boxing to settle rivalries. American Indians, East Asians and some Africans are less hirsute, and generally lack a pugilistic culture. Of all races, the European's concept of honor is most heavily influenced by pugilism. Often Europeans do not understand that the concept of honor varies by race.