It's more than that too, workflows, CI, release process are all built around GitHub (your release artifacts automatically show up on GitHub when you push a tag right?). GitLab doesn't even have "releases" in the GitHub sense; their closest equivalent is the "tags" page hidden in a submenu and it only allows you to attach some Markdown text to the tag. Issue tracking the feature: https://gitlab.com/gitlab-org/gitlab-ce/issues/41766