Ubuntu supports a wider range of devices than Debian? Since when? I was under the impression that Debian supported all or nearly all architectures the Linux kernel supports, Ubuntu only a few popular ones?
Yer it's nonsense. The first device I switched from Ubuntu to Debian on was the SheevaPlug because Ubuntu dropped support for it. Debian still supports it now well over a decade later.
AMD graphics drivers might be an example of this. They're made by AMD for Ubuntu specifically, not Debian. They work* on LMDE, so I assume they will also work** on Debian, but they weren't specifically developed for that platform.
Installing them was a bit hairy, but they've survived at least one kernel update so far, which is somewhat reassuring***.
* on my specific hardware.
** for some hardware combinations, including mine, if not all.
*** but not completely. FrankenDebian is the word I use for it.