Font Book is Empty

Hi everyone,

I'm assisting one of my coworkers and am not very familiar with MacOS or it's default software, but I had a question about Font Book.

This coworker has been trying to use Adobe Illustrator and it keeps crashing when they open certain files. Adobe recommended they restore their fonts and check for corrupt ones. I looked on their computer and inside of Font Book, there are no fonts anywhere. Literally completely blank. We tried restoring system default fonts but nothing changed and Illustrator is still crashing.

My question is: If a user has no 3rd party fonts installed, should Font Book be completely blank? Or should there be a list of default fonts installed?