Games like that, or the open-source clones of commercial games that require original assets to play (e.g. OpenXCOM), actually give a very clear analogy here: open source does not mean open assets. The software code is under a separate license from the data it processes. Emulators like Dolphin are kind of in this situation too - the program is open, the data it processes is not.

And that's fine! It's still valuable to have access to the source code, even if the "batteries" aren't included. Of course, if you really want to call it an open source model you should include the source for the data scraping/cleaning stages too; then the only thing missing would be the compute time and risk of acquiring dubiously-legal inputs.

I personally prefer a taxonomy like:

* Open weights: you can download the artifact and run it locally, not just use it through an application like chatgpt or an API.

* Open source: the code that created the artifact is provided in the same format that the authors used to work on it.

* Open data: the dataset that the source code was used on is available for download.

All three of those could be individually licensed or released, for 8 possible combinations. In the analogy to games, they would correspond to the licenses on the retail binary, the source code of the game, and the original uncompressed art assets or Blender projects, respectively.