What's wrong with Debian kernel?
https://lists.nongnu.org/archive/html/gnu-linux-libre/2017-1...
The poster on the thread you linked is making the argument that free software shouldn't be looking for non-free firmware, even when it isn't installed. That's... interesting and not something I've ever heard complained about.
The FSF doesn't endorse Debian because of the non-free repository which, while not officially a part of Debian, they consider a Debian. If you install only the "main" repository you will get only free software. The default install only contains the "main" repository.
But the post I linked to makes an interesting point abuot why ConnochaetOS is not endorsed while the same reasoning was not applied for PureOS.
It had always been my understanding that the intention is that the messages the Debian kernel displays looks like an error message suggesting that the module should have been present. Even if it looks less like an error, and is more matter-of-factly "such and such functionality is disabled because nonfree.bin could not be loaded"; reading between the lines, that sounds a lot like "install nonfree.bin for that functionality".
https://lists.gnu.org/archive/html/gnu-linux-libre/2017-12/m...
However, following the more recent discussion, particularly the comments of Alexandre Oliva (the Linux-libre maintainer), I'm not so sure. I hadn't realized that many of the extreme deblobbing measures (replacing firmare filenames with "/* DEBLOBBED /") in Linux-libre were because it must not load non-free blobs even on distros that are hostile to that goal. On FSF-endorsed distros that are not hostile to that goal, what measures are* necessary?
https://lists.gnu.org/archive/html/gnu-linux-libre/2018-01/m... https://lists.gnu.org/archive/html/gnu-linux-libre/2018-01/m...
(I am one of the core developers of Parabola, an FSF-endorsed distro)