I feel this is comparing apples to oranges. Computing platforms supporting a new runtime is less about porting existing code, but more like adding a new feature to the code base. You really don’t see much “we port our app from framework/language version X to Y” articles anywhere, except for maybe Python 2/3. But that only generally happen for one version bump for a long time. Ruby (and particularly Rails) is really not doing as well as some of other players in this area.

Django is a great product. But migrate a large project between versions multiple years apart, and you'll feel it.