It doesn't. It will work with any Adobe DRM compatible reader or app even before you remove the DRM. It will also work with their apps on Android, iOS, Windows and Mac. You do have to download from your account page to get the ACSM file but with that you should be able to use Adobe digital editions to put it on a compatible non-Kobo reader like something from Pocketbook.

Removing Kobo's DRM or the Adobe version is pretty trivial too and doesn't seem to change as much as Amazon's.

But they don't support Kindle because Kindle doesn't support ePubs and Adobe DRM'd ePubs at that.