Does the gcloud snap package include beta components?

[reusable8778]

According to https://cloud.google.com/sdk/docs/downloads-snap:
This package contains the gcloud CLI, gcloud alpha, gcloud beta, gsutil, docker-credential-gcloud, and bq commands only.

However trying to run

gcloud beta emulators pubsub start \                                                                                                            ─╯
    --project=the-project \
    --host-port='localhost:8043'

gives:
You need the [pubsub-emulator] component to use the Google Cloud  
Pub/Sub emulator.
ERROR: (gcloud.beta.emulators.pubsub.start) You cannot perform this action because this Google Cloud CLI installation is managed by an external packag
e manager.
Please consider using a separate installation of the Google Cloud CLI created through the default mechanism described at: https://cloud.google.com/sdk
/

Is the documentation wrong or obsolete?