One reason is constitutionality. The "One man, one vote" principal likely has to be upheld for a voting system used in the US to be ruled as constitutional. h

One reason is constitutionality. The "One man, one vote" principal likely has to be upheld for a voting system used in the US to be ruled as constitutional. https://www.fairvote.org/how_ranked_choice_voting_survives_the_one_person_one_vote_challenge https://www.fairvote.org/how_ranked_choice_voting_survives_t... https://www.fairvote.org/_ranked_choice_voting_reaffirmed_in_latest_court_challenge https://www.fairvote.org/_ranked_choice_voting_reaffirmed_in...