Probable cause is based on evidence.
> His hypothetical is actually how warrants are supposed to work.
No, its not.
> Law enforcement have probable cause to suspect someone of being guilty. If they can make a strong argument about why the person is probably guilty, they then get a warrant to search for evidence in homes, phone calls, emails, whatever.
And that "strong argument" is based on factual evidence that was either received through mechanism other than search and seizure, was the product of prior search and seizure in conditions that do not require a warrant, or was the product of prior warrant-based searches and seizures.
If there was no evidence left other than what was sought in the warrant, there would be no basis for probable cause to support the warrant.