It doesn't do so anymore than ubuntu already does.
Almost always, a majority of PCs for sale have Microsoft Windows pre-installed. In the rare cases that they come with a GNU/Linux operating system or no operating system at all, the drivers and BIOS may be proprietary.
Ubuntu helped enable Purism to exist and they are great for that too.
Ah, so it does so by redefining the inconvenient bits completely out of bug #1.