Opting out with the CRAs doesn't stop folks from accessing your CRs. It just prevents them from getting certain info about you and changes on your CR(s).
For a nominal fee, CAs can subscribe to your credit reports. If certain items change on your CR like added inquiries, new accounts, or drops in balances, then they will get alerted by the CRA(s) of that change. It gives them just enough information by which to decide whether or not to report. For example, most mortgage lenders will require you to pay off recent collections. If you aply, you'll get hit with a hard inquiry from your lender and if CAs are subscribed to your CRs, then they will get alerted to your mortgage inquiry. They'll usually then report knowing that you'll probably have to pay off that debt if you want to be approved.
Opting out doesn't stop them from reporting but opting out will block the flow of information by which to make a decision to report.
