The ultimate point of credit is in creating financial leverage.
Leverage means you can do more with less. Prime example being you can buy a $300,000 house even though you only have a small amount of cash available.
Leverage can work for you, or it can work against you.
The other more minor part of credit and credit cards, it's very difficult to travel without a credit card. A credit card guarantees a higher level of safety for those who are rent hotel rooms and cars. It means they are much more likely to be able to recoup any unexpected charges you might create, and on the consumer side using a credit card gives you leverage in the event of a problem with the product or service you are purchasing. As you can complain to the credit card company about problems and those large companies like Discover, Visa, Master card Amex will investigate for you. They have more leverage than you do to get results.
Try and rent a car, buy an airline ticket or rent a hotel room without a credit card and the answer on how it saves you time or effort or money will be obvious.