The confusion is that modern commercial banks don’t work like a giant vault. So applying the analogy you described to, say, Wells Fargo, would mislead you about how Wells Fargo works.
You could have a bank that does what you say, but it wouldn’t be able to survive as a commercial institution.
Most regular folks don't think like to think about banking, just like how they don't like to think about how their car engine works.
But if you ask them to describe how banking works, they'll inevitably resort to the some version of the "giant vault" analogy. Of course, that's the wrong way to think about banking. Which the article rightly attempts to dispel.
You could have a bank that does what you say, but it wouldn’t be able to survive as a commercial institution.