Is it just to bump it up, or refresh the "age" or applicant count?

Or is there some reason/rationale I missed?

 

So that they can see how you interact online professionally as well as your online persona, also known as your LinkedIn profile.

 

While I'm not an expert, there could be a few reasons behind this practice. It's possible that reposting helps to generate more visibility for the job opening, attract a larger pool of applicants, or simply refresh the listing to keep it relevant. Recruiters may also want to showcase a higher applicant count to demonstrate an interest in the position. By the way, during my online browsing, I came across a website where you can buy LinkedIn accounts. It might be worth exploring if you're looking to expand your professional network or approach LinkedIn from a different perspective.