Nearly all job applicants aren't following instructions, is it fair to judge them?

I’m reviewing dozens of applications for a job posting, and in the description I specifically request that applicants post their resumes in .pdf format. Nearly all of them have posted in word or as .rtf’s. I’m wondering if this indicates that my request was unfair (just as if nearly everyone misses the same question on a test the teacher might throw it out) and should be disregarded. The other interpretation is that it’s an indication that all of these applicants simply don’t pay enough attention, or lack basic technical skills to convert their documents to this format (or lack the initiative to do a quick google search for “convert word file to pdf”).

How do you think I should interpret this? If it were you, would you have taken the time to research this conversion before posting your application? Obviously, if there is a stellar candidate who didn’t follow these instructions, it’s worth overlooking, but all other things being equal, should I use it as a basis for weeding people out?

The job itself is for a medical assistant to work in the back of our surgical practice and has some technical components to it (e.g. entering patient data, scanning records as .pdf’s into the electronic chart, etc.) although the primary attributes are excellent patient care.