I think it is because FAQ says
We welcome questions about:
- Using and administering Ubuntu, including official Ubuntu derivatives.
- Running third-party applications on Ubuntu.
- Development on Ubuntu.
- Services provided by Ubuntu
Ubuntu one is a service provided by Ubuntu so it is on topic
I personally disagree with this , because Services provided by Ubuntu is too vague . ubuntu-one websites says
Ubuntu One was initially launched in May 2009 to provide sustainable
revenue for Ubuntu, the world’s most popular free operating system,
which is commercially backed by Canonical.
Ie, it is simply a project to earn money to support Ubuntu development. So can way say ubuntu one is a ubuntu project? My answer is only the Ubuntu client for ubuntu-one is ubuntu service,rest of them are just canonical service
Use up/down vote and comment to this opinion :-)