Some years before the DMCA became law, Debian filed the serial number off the Free Software Definition, added some confusion, and produced the Debian Free Software Guidelines (DFSG). Over the years the DFSG have suffered bitrot as copyright law and the strategies used to attack freedom have evolved. In particular, the DFSG predate the laws used to support DRM. With the emergence of the Creative Commons licenses, the DFSG have started to cause problems for free licensing, not surprisingly around the issue of DRM.
Debian (or rather Debian Legal) believe that the ability for DRM vendors to impose DRM on users is an important freedom that should not be limited by licenses. This is based on a misunderstanding of clause 3 of the FSD/DFSG and a romanticisation of the nature of DRM.
The misunderstanding of clause 3 (no restriction of where or how work can be used) is a simple one. Taken literally clause 3 means that the GPL is not free because you cannot "use" the code to produce proprietary works. This is the line that BSD apologists take. It is a simple category error. DRM can make copyleft content effectively proprietary and undo the freedoms given by the license if the license on the work does not recognise the existence of DRM. It is illogical to argue that licenses that recognise this possible removal of freedom are restrictive. A society that forbids people from owning slaves is not less free than a society that allows slavery. Restrictions on restrictions on freedom are protections of freedom, not impositions of unfreedom in any meaningful sense.
The romanticisation of DRM comes because Debian Legal are mistakenly viewing DRM as a technology rather than as a strategy of copyright law extension. Computers are a technology, so is the printing press. Their use can be regulated, and indeed this is where we get copyright from. But copyright is hundreds of years old, whereas DRM law, which is an extension of copyright, is recent. Had Debian Legal and the FSF been around in the time of Queen Anne, Debian would have argued against copyleft on the basis that it restricted printing press owners' right to use their technology as they see fit. DRM is an extension of copyright in law assisted by technological measures. This seems to make it a dog whistle for Debian Legal, who are unable to consider DRM as anything other than software or data, which freedom demands that users be able to modify as they wish. But writing "All Rights Reserved" in a GPL licensed program is simply a modification to a file. It is the legal impact of this act that removes freedom, and so users are disallowed from changing a few bytes of data in a few files in this particular way in order to protect freedom.
DRM is a way of removing users freedom. It is a way of making work proprietary. It is part of the extension of copyright law, but can remove the freedom to use even public domain works. If all it takes to circumvent the DFSG is a code element, I can easily write a shell script to remove the copyright headers from BSD-licensed code. I can even modify the files themselves to do so. Or I could were it not for the fact that BSD-licensed code forbids me from doing so. Which is a restriction on my freedom and so a breach of DFSG 3 which makes the BSD license unfree.
There will be better and worse ways of tackling DRM. Free culture licenses may well not be the place to attempt it. The way CC have done it may well not be the right way. But Debian Legal's confused and dogmatic argument against the current CC license measures based on a misunderstanding of their own guidelines and of the issue at hand, or confused and emotive pleas to "pragmatism" in favour of pro-DRM zealotry, are not sufficient cause for CC to simply abandon their current measures, or to hastily adopt a dual distribution clause.
