> Is this not exactly what enforcing copyright is since copyright dictates where and how something can be consumed?
The copyright on a (printed) book doesn't let the publisher dictate where and how the book can be read. As long as you're not making copies or derivative works or putting on a public performance you can consume it however you wish. Even on those cases there are exceptions for fair use, e.g. parody. The same applies to DRM-free audiovisual recordings. Anyone can make a player for VHS tapes or DRM-free DVDs without running afoul of copyright, but the same is not true once DRM is involved thanks to the anti-circumvention clauses of the DMCA, and that gives publishers far more power to dictate how copyrighted (or even formerly copyrighted) works can be used than they would have under copyright alone.
The copyright on a (printed) book doesn't let the publisher dictate where and how the book can be read. As long as you're not making copies or derivative works or putting on a public performance you can consume it however you wish. Even on those cases there are exceptions for fair use, e.g. parody. The same applies to DRM-free audiovisual recordings. Anyone can make a player for VHS tapes or DRM-free DVDs without running afoul of copyright, but the same is not true once DRM is involved thanks to the anti-circumvention clauses of the DMCA, and that gives publishers far more power to dictate how copyrighted (or even formerly copyrighted) works can be used than they would have under copyright alone.