Just to play devil advocate, what if the data collected is inaccurate or doesn't reflect what I am looking for, you might be showing me jobs I have zero interest in or hiding jobs I would be interested in.
- Maybe I am not active in tags on Stack Overflow in which I would be well qualified in working (possibly because the tag is a festering cesspool of low quality questions).
- What if I am looking to broaden my horizons.
- What if I am very active in tags in which I have zero interest in working in. I might be well skilled in a specific language, but I don't enjoy actually developing in that language.
Ultimately unless the user has control over what they see, basing it solely on their interactions with the site could limit the potential job seekers who see the posts and make them less valuable to both the company looking to hire and the job seeker themselves.