no-one 'advises' 18 students... this professor has a successful small business producing publications with their name on them - this is both sufficient, and increasingly all, that is required of them in academia. if their reputation is high enough you can springboard from here into your own academia-small-business start-up YMMV but you can be sure of the up-front costs!
Agreed. In the fields with which I am familiar, professors rarely supervise much more than that number of graduate students over an entire career.
But, in case of the aforementioned professor, she seemed to deplore having that many students, and it was her remark about the number of advisees that prompted the comment from the graduate school dean.
