So a guy gets a call from a prospective client inquiring about one of their services. He schedules an appointment with them. At the appointment, he is so focused on the one thing they asked about that he never bothered to find out about any other needs they might have.
Because of this lack of attention to the sales process, he missed out on other business. You see, they had other needs and didn't know that he offered solutions to them. If he had done his job, he would have asked questions about the company, identified what they needed and then let them know how he could help.
Bear in mind, he would have stayed on topic for the original reason he was called out, but he also would have paid attention to any shifts in need. As it was, he never asked, never found out, and never got more business.
He missed out on a great opportunity to go deep into that client. That's a tough thing to undo.
So, when you are at a client, or prospect, ask, take notes, listen, and find out all you can about them and their needs. You never know what you may uncover!