Sometimes that can happen but it is not common, certainly not a large % of job posts.
n of 1 and all, but most jobs I've gotten that were worth getting were from personal reference. To the extent that applying through job sites seems like a real waste of time unless I'm really desperate.
And to reflect that, the jobs I've gotten were the ones you'd only accept if you were really desperate.
(Covid Times, man: Covid Times.)
Do you have a source on that?
It would be genuinely shocking to me if someone came up with evidence that the majority of jobs on job sites were made by companies that actually intended to hire the best candidate that applied through that site!