In this context, not everyone’s first choice, but the one that the majority could support against each other candidate individually.

For example if you have candidates A, B, and C, with 35%, 31%, and 34% of the 1st choice votes respectively. B gets eliminated. Only 50% of their voters put down a second choice, and their 2nd choice votes are almost evenly split between A and C, but slightly favor C. So lA and C end up with 49% and 51% of the remaining votes, respectively and C wins.

However, basically everyone that didn’t put B as their first choice did put them as their second choice because they did NOT like their ideologically opposing candidate at all). So, if A hadn’t run, the results would have been B with 65% of the vote and C with 35%. If C hadn’t run, the results would have been B with 66% and A with 34%. Either way, B would have won by a landslide in those races, but instead B got eliminated in the first round which gave C the narrow win.

It seems like that maximum number of people would have at least approved of the outcome if B had won. Instead, only a minority of people people’s votes ended up deciding the winner and everyone else sees the outcome as unfavorable.

This is I prefer approval voting. Two candidates never have to have split support and there is no worry about unsure elimination. So long as everyone honestly votes for whomever they would approve of, the candidate with the most support will win.