It is difficult to check the status of a PO, and the way you do so is inefficient.
You need to manually track quotes or use third-party software. You manually enter transactions to accept deposits and have to manually update the general ledger accounts.
You manually track orders and may use a program such as Excel. It is difficult to tell whether or not items are in stock. You need to wait until the stock is replenished and manually enter the order at that time.
You have to wait until the order is filled and then manually update inventory. That gives an inaccurate picture of inventory levels.
You manually track orders, and your method of processing backorders is inefficient. You need to wait until the stock is replenished and then manually enter the order at that time. It is difficult to keep track of which customers still need orders filled.
You do not know when you are getting low on inventory, and as a result you run out of stock. This has a negative impact.