Harriet Miers didn't go to an Ivy League school, but she also never served as any type of judge, and had no other background in constitutional law like litigation or academia. Now, in previous generations people with no direct judicial experience were appointed to the Supreme Court and served well, like Earl Warren, but this has not been customary for quite some time, and Miers did not have massive outside accomplishments like Warren (3-time Governor of California).

Miers was just tremendously unqualified for the job and was nominated because she was really close buddies with GW Bush and GWB lived his whole life based on personal loyalties and relationships.