For most of the last century, businesses reached customers through newspapers, magazines, television, radio, and billboards. If you wanted to be seen, you paid for space — and hoped the right people were paying attention.
There was no way to know exactly who saw your ad, whether they acted on it, or what it actually returned. A business could run the same campaign for months without ever knowing if it worked.
Marketing was a leap of faith — expensive, one-directional, and built on guesswork rather than evidence.