Yup. An extremist wing of the FOSS movement ceded the debate early on by trying to insist open source required full access to the training data. Philosophically, not wrong. But practically fucked, so the word evolved.
Within tech circles, open weight != open source. Outside them, they’re synonyms.
Example: The first time I saw the New York Times use “Open Source” in a headline, what they meant was open weights.
also, you can do a lot to finetune or repurpose an open weight model. much more easily than you can mod closed source binaries.
Training data without the training regime is useless. A cake is not open source because they list the ingredients.