Is it necessary to install the gcloud component that includes the App Engine extension for Python?

[Mori via StackOverflow]

I have an App Engine application in Python. I can deploy it simply by installing and initializing the Google Cloud SDK. But according to the documentation:

The default installation does not include the App Engine extensions required to deploy an application using gcloud commands. These components can be installed using the Cloud SDK component manager.

It also mentioned in Download the SDK for App Engine: I just took the second step and then deployed my app.

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