You keep the listed price from falling behind cost
Before, the price only got fixed when someone noticed the gap or a customer complained after checking out. With the review tied to the moment the cost changes, the listed price keeps up with the replacement cost instead of waiting for a fixed review cycle. That cuts down on selling below what the product costs the store today.
You stop showing availability that doesn't exist
Before, a sold-out item could stay listed as available until someone tried to buy it and found out there was none left. With availability updated the moment stock moves, the store avoids closing an order for a product it can't deliver, cutting down on cancellations, apologies, and having to fix the problem after the customer already expected the order confirmed.
You stop relying on memory to update prices
Before, fixing price and availability was a task that depended on someone remembering to do it, which delayed changes and left products outdated for weeks. With the event-based criteria (cost changed, stock moved, item ran out), the update happens at the right moment, even without anyone reviewing the whole catalog. That cuts the chance of a product staying wrong for lack of time or memory.
You end up with a record of what you checked
Before, even when someone fixed a price or an availability, there was no record of when it happened or why. With the note listing the product, the change made, the time, and confirmation that the active catalog was updated, the store builds a history of checks. That helps show, if needed, when an item was last reviewed and what changed at that moment.