Nonsense.
There is an incentive to cheat any time there is a test, where capabilities are measured that are not routinely used.
For example, if I were an engineer designing an elevator, it must meet its rated load limits times a hefty safety factor. That safety factor is a test, and if I were unscrupulous then I would have every incentive to "cheat" to falsely certify compliance. Under ordinary circumstances, that safety factor is left unused when the elevator is operated as per instructions, but the cheating covers up a latent problem with potentially catastrophic consequences.
An academic degree isn't about a worthless piece of paper; it's ostensibly certification that the student has an acceptable mastery of the course material. Much of that material won't be used on a day-to-day basis, but it's still there, and it's still part of the credential that the graduate holds out to the world.
But even if you're unconvinced by that, there's also the character signal at play. The "kind of person" who will cheat on an academic test is intuitively also the "kind of person" who will cheat in other areas of their professional life.