Google has decided to include hardware vendor’s patches into their monthly patch levels as well. On other OSes those are often separate, so they get less attention.
The underlying problem exists on computers as well: drivers are closed source and vendors can decide any moment to stop updating them. On Windows, you won’t notice that unless you upgrade your OS from Windows 7 to Windows 10 (for example); you can continue to run drivers that are years old on Windows 7 just because 7 has been around since 2009 and is still supported at the moment.
On Linux it is less bad indeed as you do get kernel updates, but there you also have to deal with closed drivers for graphics/wifi at times.