I work in a niche field. Most people have never heard of it and would need a 20-minute session to begin to understand it (but they are usually not that interested!).
With some of the job postings in my field, you can tell that they were written by someone who doesn't know about it. Probably by an HR person who fills all kinds of jobs and doesn't have time to learn about them all. The problem is, the postings don't make sense. E.g. They list redundant, contradictory or outdated requirements, or the requirements are missing something that should be there (such as current technologies). So, it's difficult to write a resume that gets enough "hits" for keywords, without cramming them in. Should I just cram them in? What about info that is relevant to the job, and an important part of my experience, but won't get picked up in a keyword match because it's not in the posting?