Reading some books on iOS Pentesting I noticed that almost all tests or tools require a jailbroken device.

I looked for information about this, because it is needed to perform those tests or to use those tools, and I understood it.

But I cannot found an explanation on this doubt:

In the real world not all devices are jailbroken, so how relevant are test results using a jailbroken device in a real context?

EDIT

Can I assume that an application vulnerability once found in a debugging environment, it should be replicated on a non-jailbroken device to become validated?