You keep the contact without relying on anyone's memory
Before, you depended on someone remembering who asked what, and that memory disappeared the moment they went on vacation, changed roles, or just forgot. With the four fields logged on every inbound conversation, that information exists outside the head of whoever answered. That lets anyone at the store pick up a contact without asking whoever talked to them first.
You know who agreed to be messaged again
Before, you assumed it was fine to message an old contact, with no certainty the person had actually agreed to keep talking. With permission logged along with everything else, the store tells apart who agreed to hear about new arrivals from who just asked a price once. That cuts the risk of reopening contact with someone who didn't want to be reached again.
You recover old conversations instead of losing them
Before, you turned a contact with no record into a name with no context, buried among dozens of other chats, hard to find and even harder to understand weeks later. With the date, name, and interest written down, the store can open that contact months later and know exactly what was at stake. The conversation doesn't have to start over, even though it had already moved forward before.
You keep the same record no matter who answered
Before, you and your team each kept the information a different way, or didn't keep it at all, leaving gaps that were hard to notice until the contact was already gone. With the same four fields required for every inbound conversation, the record stays consistent no matter who answered that day. That makes it easier to hand a contact from one person to another without losing information along the way.