Allow disabling a cluster integration via the API

In the documentation https://docs.gitlab.com/ee/api/project_clusters.html enabled flag is only available for the Add project cluster endpoint. The documentation is correct, since I've tried it also with raw API calls.

Once you create a project cluster that is disabled, you cannot enabled it back via API. You have to do it via GUI.
Also the get endpoint does not return this value.

Is there a special reason behind this?