Habit doesn't mean highest efficiency. With email and phone orders, each order requires a sales team member to manually receive, confirm, and enter it into the system, and both parties end up waiting for responses from each other.
Self-service online purchasing allows customers to place orders anytime, check order status, and even quickly duplicate previous orders without waiting for sales staff to be available. For the sales team, the time saved goes beyond order entry—it eliminates all those back-and-forth confirmations like "Did you get it?" and "Let me check."
The time freed up can be spent on work that truly requires people: discussing new products, negotiating prices, and handling exceptions. For customers, they gain control over the process and don't need to wait for a person to respond, creating a better experience. The switch does involve some friction, but once customers experience the self-service flow, they typically don't want to go back.