The only schools that do not have AOA chapters are Harvard, Stanford, and UCSD. Students from these schools tend to do well in the match. While there is a bias at many top residency programs against applicants who are not AOA, students from schools that don't have chapters check a box on their ERAS residency application that says "my school doesn't have AOA". What many program directors do for students from these schools is to look for "AOA equivalents", such as if they have outstanding clinical evaluations, research experience, other extracurricular activities, good board scores, etc.
There are several other schools, such as Yale, who wait to announce AOA until after the match, so it can't be used for residency selection.