Cryptozoology can lead to the disovery or rediscovery of organisms but the field itself is about studying the "unknown." Cryptozoology is about studying things that have failed to be proven alive thus starting with a conclusion, "this organism exists and is related to (whatever animal)." Once the Thylacine is rediscovered any study would ultimately just become zoology. Cryptozoology is the working on the discovery and the classification before discovery.
For example if you tried to classify and identify the Coelacanth based on eyewitness and first-hand accounts of the local people before discovery that would be cryptozoology. Now if you were to study the fish you would simply be a zoologist unless studying it would contribute to some other cryptid or cryptozoology related topic.
Technically cryptozoology is a pseudoscience but the fact that it's not viewed very well in the light of "true science" bugs me. I cannot even try to comprehend people who think that there's not more out there than we already know, and unfortunately, a lot of scientists are like that and are not willing to change their scientific views of the world for that.
Granted, there are a lot of more questionable things in this field that would cause us to look kinda like a joke. For example, the lack of the Occam's Razor principle (which is not used as often as it used to be but still).