Say you're talking to your friendly neighborhood CBP officer and they say this:
"I think you're an immigration risk and, accordingly, I'm issuing an Order for Expedited Removal. You get on the next plane back home." Your passport gets tagged with a 5 year timeout.
However, they could say something like:
"I think you're not eligible for the Visa Waiver Program, because some factors suggest you're an immigration risk. I recommend you withdraw your application for entry into the United States and voluntarily get on the next plane back home." You will not get timed out for 5 years.
Note that the second one is neither a recommendation nor a request.
Disclaimer: IANAL but IA someone who has to have an anomalously-good-for-most-Americans understanding of immigration procedure.
But you're much more vulnerable if you bring data with you. The first level of protection is making a backup, formatting your devices as new, and restoring once you're on US soil. Better yet is not bringing devices at all. But certainly don't bring secrets with you: bank records, medical records, and military secrets should never be carried with you through customs.