I used to work in recruitment and often a resume does stand out and the person just "looks" like someone you need to interview. Other times a resume actually hurts the candidate and underwhelms the reader and the person doesn't get an interview. Remember that hiring managers don't hire profiles or resumes they hire people. So when you ask why people with good profiles (NOTE: good in the eyes of who, though?) aren't getting good jobs, are you really asking:
1. Why aren't they getting interviews: In this case perhaps their profile isn't as good as you think. Maybe they have a great profile and background but maybe they're applying for the wrong jobs.
2. Why are they getting job offers: In this case, maybe they're getting interviews but aren't doing well in the interview process which is something completely different from point #1.
I always used to have candidates teling me after an interview that they did really well in the interview and some even told me that they should be getting a job offer because they have everything the employer needs. But unless they know all the other people who are also interviewing for the job, how can they really tell?
Bottom line: you might have a great profile but there might be other factors that are causing you to miss out on jobs. You need to figure out where in the process you are failing ie. resume, interviews, reference check stage, etc.