Ah, that is the genius of it.
More people want jobs than there are jobs available.
So, the primary job is to keep people out.
Most people will be kept out because there are more people that need to be kept out.
There are many methods of keeping people out.
You can pass every trial and tribulation in the requirements and then find yourself in trouble because of a single piece of paper – even if you know somebody in the company, even if you have worked there for a while.
Once upon a time, for me it was a high school diploma. I was already working there for a while. But one day, somebody in HR noticed I didn’t give them my high school diploma.
SO I had two weeks to show it to them or I’d be fired. My boss wanted me. My co workers wanted me. I was useful.
It took a few days to find it, and I did and all was fine.
But that is an example I almost went through that demonstrated for me their primary purpose is to keep people out.