alt Hacker News> They are talking about "storage devices" in that context, which is a total misread
What misread are you talking about? I'm talking about storage devices because the documentation says you can't update macOS on an external storage device while it's connected to the DFU port.
> their interpretation of DFU seems to be something close to "default boot device."
No, that's not my interpretation. I have no idea where you're getting that from the blog post.
Fair enough. I now see the connection (i.e. separate from DFU process another doc excludes DFU designated port from participating in your process.) Regardless the documentation is 100% correct re which port is DFU port. If your process fails, it could be for any number of reasons only one of which has to do with using the DFU port, so it is not a logical implication to conclude the failure means DFU port is wrong.