As anecdata, I’ve worked in recruitment, both as a recruiter and as CTO of a very well-established recruitech firm, and basically have never heard of this outside of people complaining they think it happens. Posting jobs you already know who you want to hire for it, sure, but the signalling success and luring in candidates for later thing wasn’t really something I saw. To me, it feels like when people used to claim that antivirus firms were the ones writing viruses.