A good tech interviewer would be screening
out candidates who prepared for tests but didn't have real skills. It would be funny, and sad, to watch someone ace the FizzBuzz question but then choke when the parameters were changed a little.
Standardized testing in schools perverts and devalues education, producing graduates who mistake passing tests for learning.
Imagine working alongside people who got hired because they knew how to answer interview quesions, but didn't know how to do anything useful. Imagine reporting to a manager who thought a good hire was someone who knew all the answers to their interview questions.