Devil's advocate here (and an employer).. Its common for thousands of applicants to respond to a posting, many of whom are not vaguely qualified. So when a position is filled, its not uncommon to be turning down several thousand people. Honestly, do you want to send a disappointing email to 3000 people and then deal with the responses? More importantly, do you have time? Remember, wasting time on the wrong problems i…
When company has a job opening - they want to fill it ASAP, so they want to see multiple resumes, not few. Even if these resumes are not 100% relevant.
In order to deal with high volume, recruiters choose not to reply to not very relevant applications.
In order to fix it, job board must be able to filter irrelevant applications, but realistically only recruiter [somewhat] knows if application is relevant or not.