Why ask to connect if you already filled the role?

I randomly get connection requests on LinkedIn. Sometimes they add a note about a role.

I decided to accept this one who did. Said it was a recruiter. Looking to fill a role about something I’d be great for. I sent over my resume like they asked. I asked about next steps. They said that oh it was old post. I already filled it.

I got the request an hour ago. WTF