I don't particularly love gmail and I'm personally trying to switch to fastmail over time, however I am on google's side this time around. There are reasonable approaches that can address this librarian's concern. Backup codes, backing up the MFA seed. She talks about patrons having cell service shutoff, but that doesn't affect google authenticator. There are good reasons why google went to an MFA only model and yes there are some downsides, but they're not unmanageable.