My guess would be an inability on the part of those who wanted inconsistent signatures to be a valid reason for throwing out a ballot to show evidence that such

My guess would be an inability on the part of those who wanted inconsistent signatures to be a valid reason for throwing out a ballot to show evidence that such a move would prevent widespread fraud, and a significant amount of data on the part of those arguing that signature verification would instead disproportionately throw out qualified ballots filled out by people whose signatures vary sometimes (my certainly does).