As somebody who has helped define the objectives for & write questions for some CompTIA exams, you are in the right ballpark, but not quite right.
CompTIA targets most of their exams as entry level exams, for somebody who has been doing workstation (A+), basic server (Server+), Linux (Linux+), etc. for about a year. They are not meant to prove you are an expert on the subject, just prove you probably know the basics.
My personal opinion is a cert will never get you a job, but they might get you the interview. They are good for getting past HR or automated filters who might not know UNIX from Perl, but can tick off requirements based on certs. Also, all things considered, somebody with a cert has a slightly higher chance of knowing their stuff. Of course you have to be able to prove it in the interview when confronted by knowledgeable people.