Why is an accounts receivable ledger or an accounts payable ledger necessary for a business with large

Question:

Why is an ledger or an ledger necessary for a business with large numbers of credit customers or large numbers of vendors / suppliers?

Accounts Payable
Accounts payable (AP) are bills to be paid as part of the normal course of business.This is a standard accounting term, one of the most common liabilities, which normally appears in the balance sheet listing of liabilities. Businesses receive... Accounts Receivable
Accounts receivables are debts owed to your company, usually from sales on credit. Accounts receivable is business asset, the sum of the money owed to you by customers who haven’t paid.The standard procedure in business-to-business sales is that...