Can you imagine the chaos if elections were not required if the other candidate "conceded" before the election. It will lend the other side the ability to apply pressure tactics until they "conceded".
I lived there. It DID happen exactly the way you described. Yes, it was ugly. The white candidate who finished first conceded because the campaign was getting so ugly. The runoff was cancelled.
I recall Vermont has (maybe had) a requirement that the governor get a majority vote, with the legislature deciding among the top two finishers if no one had a majority.
A few years ago the top candidate finished with slightly less than majority but the #2 finisher waived his right to a runoff in the legislature.