In warm countries, Ali sits under a tree a few steps from the US consulate with a chair, a small table, and a manual typewriter. In cooler countries, he rents a tiny office a few steps from the US consulate with a chair, a small table, a manual typewriter and a space heater. He doesn't put out a sign; he doesn't need to. He strolls to his work station - accepting respectful greetings from the queue of consular customers with great dignity - and sets up his typewriter every morning an hour or so before the consulate opens. Then he nods to his first customer.
So when a consular officer refuses a nonimmigrant visa applicant 221(g) for any document that isn't required by the visa application, the applicant goes to talk to Ali. For a reasonable fee, Ali will provide the form or letterhead, the data, the signature and the seal. The applicant will return to the consulate and turn in the document. The consular officer will issue the visa and the applicant will travel to the US. Ali will deposit the modest fee - along with a dozen or two or three dozen other fees collected that day - in the education fund he has now opened for his grandchildren.
Wait a moment, you might say. What do you mean by 'any document that isn't required by the visa application?'
Documents that are required before a visa can be issued are forms like I-797s, DS-2019s and I-20s. Anything that is not required is irrelevant and should not be asked for; if offered, it should not be accepted. Why? Because it is irrelevant, it is distracting, it invites dishonesty, it substitutes for actual knowledge, and it keeps Ali employed.
But wait a moment, you might say. I need a (job letter, property deed, bank statement) to be sure that the visa applicant is what he claims to be.
No, you absolutely don't need a document to tell you this.
Then how will I know that he is what he claims to be?
You will interview him. And Ali's grandchildren will have to pay for their own educations.