As I gather from this document, it is the user/holder that creates proof of non-revocation (of a credential) that a verifier can subsequently check for correctness. This provides a verifier with assurance that the credential he has received from the user has not been revoked at the time that the proof was created (and sent to the verifier).
However, verifiers need to have this assurance for the time at which the data in the credential is actually used. The time between the creation of the proof and the use of the data in the credential may be very short, but it may also be very long: days, weeks or even longer.
Here is an example. Consider the situation where Alice needs a permit to park in the street where she lives, and she decides to file an online application form on friday afternoon at 16:47 pm. She provides her credentials, which contain claims about the car she owns (licenseplate), that she has a valid driving license, that she lives near the place where she wants to park, etc. Also, she provides the necessary proofs of non-revocation. Civil servants don’t work in the weekends, so decision making is deferred to at least Monday morning, after coffee. During the weekend, Alice may be caught speeding which causes her driving license to be revoked, or she can sell her car causing her car-ownership credential to be revoked. After the weekend, the civil servant that decides on her application cannot tell whether or not any of these events occurred.
Use-cases such as these call for a new or updated revocation mechanism that allows verifiers to check whether or not a credential it has received, has been revoked at any point in time after having received it.
Having such a revocation mechanism has various other benefits. For example, it would allow the organization that issues parking permits to check every now and then whether or not the permits it has issued need to be revoked because one of the premisses on which it was issued has been rendered invalid (expired and/or revoked). This also allows (parking permit) issuers to issue credentials (permits) that need not be renewed every year (which often means that the applicant needs to reapply every year); it suffices to regularly check for expiration and non-revocation of the credentials that underpin the issuing decision, thus saving a lot of bureaucracy.