Thank you. That's an excellent question.
Not having access to their immigration file and specifically to the documents that IRCC already holds can have many negative impacts when an applicant is doing a subsequent application.
When an applicant submits an application online using the CIC portal, they are not given a copy of what they submitted. Once it's in government hands, it stays with the government.
Increasingly, when you have digital applications, hard drives crash, computers are exchanged and applicants can easily lose track of what they have submitted. When an applicant cannot access their previous files, they can't understand why their application was refused. Without notes, they don't know what the officer's reasoning is without access to the files to do their own due diligence and review whether a signature was missed. They can't determine that.
Thus, when there's a very long delay and an applicant is refused, they have to wait the entirety of the delay until they can apply again so that they can make a strong application that will overcome the reason for refusal.