On the other hand, cloud software is often more convenient to use, allows for syncing on multiple devices, and is more powerful due to having access to the comp

On the other hand, cloud software is often more convenient to use, allows for syncing on multiple devices, and is more powerful due to having access to the computing resources of large data centers. So you can't really say that building cloud apps is only a downside. Tilt brush just happens to be the type of application that doesn't overlap much with these benefits, making it easier to open source. Also, cloud software isn't much more difficult to open-source, see self-hosted open source applications like NextCloud: https://nextcloud.com/ https://nextcloud.com/