Releasing weights even with permissive license, doesn't technically make it "open-source", unless all the method, data and technical inner working to do it is also released. Otherwise, it's just a binary floating in the wild, even if it's under MIT.

Nobody is going to upload 1PB of data for you to download.

I would compare them more to media released under the creative commons license.

For example, you can record yourself playing different instruments, singing, and making other sounds. Then you can go combine all these recordings into a song, and you release the song under a CC license. The CC licenses framework does not demand that you also release the component recordings. But the released song can be remixed by someone else.

(Not making a value judgement, just making an equivalence).

It's effectively shareware. What was old is new again.