Traditional advertising grew out of the old distribution model.
Companies made their product, sold it to stores where people buy the product, and those stores sold it to the consumer. This worked for everything from toothbrushes to televisions.
Then these huge companies wanted to increase sales of their product. Since all of the competition is right on the shelf, they needed to differentiate themselves from the other products.
One way was price: sell the lowest price product. But the better way, and a longer term solution, was branding.