Here is the quote (from the 3rd ed., page 41):

"In general, the least effective methodology of all is random-input testing—the process of testing a program by selecting, at random, some subset of all possible input values. In terms of the likelihood of detecting the most errors, a randomly selected collection of test cases has little chance of being an optimal, or even close to optimal, subset. Therefore, in this chapter, we want to develop a set of thought processes that enable you to select test data more intelligently."

You can immediately see the problem here. It's optimizing for number of tests run, not for the overall cost of creating and running the tests. It's an attitude suited to when running a program was an expensive thing using precious resources. It was very wrong in 2012 when this edition came out and even more wrong today.