What is the usefulness of the analysis of accounting records for a secured credit 100% by collateral such as securities displacements?

When a  lender assesses a company for lending, he needs to look at the repayment capability of the client. The repayment is expected to be generally from the cash flows generated from operations.

Even if the credit is 150% secured, if the lender is not satisfied with the repayment capability of the client, then he would not recommend the same. Though the major reason is as discussed above that the source of repayment should be cash flows from operations, another reason could be that a lender cannot bank on the value of collateral - be it land / building, plant and machinery as the value is subject to change any day.