I find this distinction of focus between OS and FS interesting, but a little off. though the definitions are essentially equivalent, underlying values aren't. while FS has always been about freedom for users, because users deserve to control their computing as a human right, OSS shifted that to freedom for developers, which makes sense in their rebranding to appeal to corporations, even at the expense of users' freedoms. for OSS, users' freedoms matter to the extent that users might become contributing developers. so I don't think it's about binaries vs sources, it's about whose freedoms are on focus. as a counter-example to the binary vs source distinction, even a small source code fragment is a valuable piece of free software.
that said, it's true that OSS cares less than FS about binary-only components, but that's not because of binary vs source, it's because redistributing a blob is not a problem for a developer, while it is a killer for a freedom-seeking user. (I acknowledge developers are highly inconvenienced when having to interact with black-box blobs; these days, most driver developers that interact with firmware blobs have access to both, they just aren't allowed to share details on the blobs)
the same difference of focus applies to other freedom-depriving techniques that harm users but not developers, such as tivoization. technically, tivoized software does not meet the OSS def, but OSSers don't care because it doesn't hurt developers.