A place where this idea falls down now is many devices do not actually contain a ROM. They only have RAM and get their firmware loaded into them at initialization. Functionally they are little different from a device with a flashable firmware.
This is a weird situation for Linux distros or any FOSS operating system. In order to use this hardware they need to ship closed binary blobs. Even if the license on the blobs allow redistribution shipping non-free software is often against a groups internal rules.
Peripherals requiring firmware from the host are not new. In the consumer PC market, software modems (or "winmodems") appeared in the early-to-mid 1990's.
A device with only RAM that gets proprietary software loaded into it from a storage device on startup is the description of any computer booting a proprietary operating system.
The GNU Public License contains an exception allowing GPLed programs to link to the libraries of an existing installation of a proprietary system.
The situation that is different with firmware blobs is that you have to redistribute them. Even if you get rid of the proprietary OS from the host machine, your free OS has to supply those blobs.
This is a weird situation for Linux distros or any FOSS operating system. In order to use this hardware they need to ship closed binary blobs. Even if the license on the blobs allow redistribution shipping non-free software is often against a groups internal rules.