> Firms accepting only a single candidate CV from a recruiter instead of 5 or more

Why though? I've done hiring before - it takes less than 30 seconds to skim a resume. The recruiters also have no idea what the responsibility is for the jobs they are hiring for - it's a terrible place to bottleneck candidates on.

It sounds like everyone, including recruiters, are being sent on a snipe hunt.

I would guess that with bots and AI, a lot of resumes are not even from real candidates, and those that are, are AI slop. I don't envy recruiters or hiring managers these days.