People applying to those postings describe it as a closed door. One of them wrote: "How's someone supposed to get started if every beginner role wants you to already know the job?" The thread.
The replies on that thread are theories: employers can be picky, the line says preferred rather than required, companies would rather wait than train. Those are comments, not a measurement. We do not pick one and publish it as the cause.
A graduate asking whether to apply anyway is a different question. Career-office pages often say yes. One librarian's site suggests applying around 80 to 90 percent of the requirements. That percentage is their rule. It is not a finding, and it is not ours.