I should have said conditional customer data. (Client lists, phone numbers, email addresses - basically whatever you can export out of Salesforce)
In order to poach your old company’s customers, you’ll need confidential data from your prior employer, assuming that your employer doesn’t publish their client roster publicly.
The debate is being dragged from poaching customers to how IP protections enable monopolies. That’s too big of a leap to be relevant in this thread (sorry for saying IP rather than confidential data)