I don't know if that's fair to say. While you might argue that you don't personally fit into a clearly defined category called 'premed', you have to admit that there is a steriotype, a set of urban legends, a set of goals, even a similar set of challenges that all 'premeds' encounter. As a 'premed', that is to say an undergraduate with some intention to attend a medical school, you have quite a few experiences in common with all the other 'premeds' around the world.
Not only do you take many of the same classes (physics, bio, chem, ochem, calculus...etc) but you worry about some of the same things (only 4% of applicants get into Harvard! The average score on the MCATs is a 28! There are kids out there who sabatoge labs!...etc) and you face some of the same challenges (AMCAS, MCAT, Interviews...etc).
The reason why there are so many bulletin boards for Car Racing fans, Cancer Patients, or Premed students is that there are clearly people who are Car Racing fans just like there clearly are people who are Premedical Students.
So I have to disagree. I think there is definitely something called a 'Premed' and I think it is possible to clearly define what that is. Not to say all premeds are the same, and I don't think they share as similar an experience in their lives as medical students do, but I think someone could write a book about Premeds that we could all relate to, becase in some way or another, despite our best intentions, we are all 'premeds'.