When something is called an open-source alternative to something else, doesn't that imply that the latter isn't open-source? But Moodle is.
Canvas : AGPL : Rails
D2L : Closed : C#
Blackboard : Closed : .Net?
Google Classroom : Closed : Python?
Sakai : Apache : Java
To me it seems like another business attempting to leverage the open source community to bootstrap a product before they monetize it.