To understand why a patcher is often sought after, it's important to look at the evolution of the software:
Helping systems recognize libraries that may have been saved in a newer version of Kontakt so they can be opened in an older one (where technically possible). Kontakt 6-7-1 Patcher
Native Instruments cannot provide technical support for software that has been modified by a third-party patcher. Conclusion To understand why a patcher is often sought
Bypassing the "Service Center" or "Native Access" requirements to add third-party or custom libraries to the Kontakt "Libraries" browser tab. Kontakt 6-7-1 Patcher