No, you’re not wrong. The framework is the real library used by GCF whereas the emulator is a fake imitation of the GCF server.
The main benefit is that the framework is used by the actual Google Cloud Functions product and that it is portable across different environments.
Fantastic considerations when considering serverless.
Serverless pros and cons:
+ Save time, easy management
+ Good for batched API requests and GraphQL
− Suffer cold starts
+ Cheap for sporadic utilization
− Expensive for heavy utilization / many API calls