There is some overlap depending on whether the question involves local programs or not.

* If the question is about a local application (e.g. Photoshop CC), then it would be **on-topic**.

* If it were about the interaction between a local application and the online service (e.g. uploading from Photoshop CC), it would be **on-topic**.

* If the question were about the use of a solely remote service (e.g. online management of files) it would probably be **off-topic** and better suited to [Web Applications](http://webapps.stackexchange.com/).

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As for usage, I (and probably some others) actually do use Adobe CC - but sometimes we just don't know, or maybe didn't see the question. And of course many people subscribed to the other tags wouldn't be notified. [Your own question](http://superuser.com/questions/685119/what-limitations-are-there-when-i-try-to-run-an-adobe-creative-cloud-application) is a rather obscure use case, and I wouldn't be able to answer that. I'm not sure how many others would have the setup and time to test it, let alone find themselves in the same situation.