Why host your project on Drupal.org

Contributors are strongly encouraged to host themes, modules, translations and installation profiles at Drupal.org rather than elsewhere (GitHub, BitBucket, your personal site, etc.) for the following reasons:

• Community owned - By hosting your valuable project on Drupal.org you are protected against external interference from corporations. Why? Simply because Drupal.org is owned by both you the community users and the not-for-profit Drupal Association (DA). The DA first priority is to serve you the users. In other words, per its mission, DA value people above money. Also, Drupal.org is owned by the DA. Not by a Corporation. Corporations are really welcome, but as contributors to your project. Not as owner of your project.
• Larger User Base - Most users check Drupal.org first and assume the project doesn't exist if it's not there.
• Consistency Is Understandable - It is much easier for someone new to Drupal to understand how to download and install themes/modules from a central location rather than 3 or 4 central locations
• Unified Issue Tracker - "My Issues" will show any issues you are subscribed to for any Drupal project, instead of having to go to different sites to check
• Security advisory coverage Once you have successfully applied for security advisory coverage the Security Team will assist you in resolving security issues and publish security advisories for stable releases of your project, if needed.
• Usage Statistics - Any project or theme on Drupal.org has tracked usage statistics via the Update Status module
• Update Notifications - A Drupal website will notify (even email if you prefer) you when a Drupal.org project is updated via the Update Status module
• Programmatic Updates & Downloads - Hosting everything at Drupal.org means that Drush, Aegir, Plugin Manager, etc. can all have a uniform method of downloading and updating projects.
• Encouraging Activity - Users are more encouraged to contribute bug reports, patches, etc., if they only have to do so in one place, with one account, and one set of skills.
• Co-contributors - It is trivial to add more git contributors to your Drupal.org project, and more difficult if these contributors would have to be set up in an external site
• Install Profile Integration - Drupal's Install Profiles give you pre-packaged versions of Drupal, complete with all required modules and themes. They cannot do this if any of the modules or themes are not hosted on Drupal.org.