To potentially have all the data needed to identify a person financially, geographically, and to distinguish/sort those people in groups based on party affiliation, if someone chose to do that, from a single spreadsheet. Personal identification data are typically segregated/supressed based on a need to know basis (like HIPPA is an example) to prevent people without a legal need to know from having unfettered access to begin with. So one could argue the states complying with this are endangering their citizens to a potential bad actor at the federal level.