Why do recruiters ask for 3 years of experience for entry-level jobs?

So the reason why I would ask is that I feel that no one (the employer nor the candidate) should ever want to fill a job with someone who is "fully qualified". I know that sometimes a tight market might mean that there are lots of fully qualified candidates and that presents for me a conundrum. In general though I would recommend to a candidate that they should always seek jobs they are not fully qualified for. Missing two years of required experience, no problem that is an opportunity for growth and an opportunity to explain that if you get the job it locks you into the opportunity. No employer really wants a fully qualified candidate that is constantly looking for a job opportunity where there is growth.

Whatever we think about the entry-level job market, it's far worse and has been for decades.

I have 5 sons who become adults and tried to enter the job market. All of them were gatekept by portals that (by every indication) silently auto-discard applicants with no job history (100% of new job seekers).

My sons got zero replies, for countless jobs that they absolutely could have done well.