There seems to be convenient ignorance of copyright protection for the works displayed here at deviantART. I say convenient because the people claiming they have "every right" to steal works from others should, and often do, know better. The purpose it is often to "puff up" their own galleries, but there is a smaller number of individuals who steal with the purpose of monetary gain, be it through the sale of prints or by using the stolen works to generate "traffic" on their commercial websites. They then use this traffic to generate income. Clearly theft.

As for those not familiar with the concept of copyright, here is a copy of how copyright is conferred to any work (this is from the U.S. Copyright Office, you can reach it here [link]):

"How to Secure a Copyright
Copyright Secured Automatically upon Creation

The way in which copyright protection is secured is frequently misunderstood. No publication or registration or other action in the Copyright Office is required to secure copyright. (See following note.) There are, however, certain definite advantages to registration. See “Copyright Registration.”

Copyright is secured automatically when the work is created, and a work is “created” when it is fixed in a copy or phonorecord for the first time. “Copies” are material objects from which a work can be read or visually perceived either directly or with the aid of a machine or device, such as books, manuscripts, sheet music, film, videotape, or microfilm. “Phonorecords” are material objects embodying fixations of sounds (excluding, by statutory definition, motion picture soundtracks), such as cassette tapes, CDs, or LPs. Thus, for example, a song (the “work”) can be fixed in sheet music (“copies”) or in phonograph disks (“phonorecords”), or both. If a work is prepared over a period of time, the part of the work that is fixed on a particular date constitutes the created work as of that date."

Also so that there is no doubt the works here at deviantART are indeed covered, read the following, also from the U.S. Copyright Office,

"What Works Are Protected?

Copyright protects “original works of authorship” that are fixed in a tangible form of expression. The fixation need not be directly perceptible so long as it may be communicated with the aid of a machine or device. Copyrightable works include the following categories:

1. literary works;
2. musical works, including any accompanying words
3. dramatic works, including any accompanying music
4. pantomimes and choreographic works
5. pictorial, graphic, and sculptural works
6. motion pictures and other audiovisual works
7. sound recordings
8. architectural works

These categories should be viewed broadly. For example, computer programs and most “compilations” may be registered as “literary works”; maps and architectural plans may be registered as “pictorial, graphic, and sculptural works.”

Now, what can be done when your work has been stolen, certainly deviantART has every right to take action against such violations, and so do the artists affected by those violations. The following is some remedies available, through court action, particularly against commercial sites involved in theft, again the source is the U.S. Copyright Office,

"§ 504. Remedies for infringement: Damages and profits

(a) In General. - Except as otherwise provided by this title, an infringer of copyright is liable for either -

(1) the copyright owner's actual damages and any additional profits of the infringer, as provided by subsection (b); or

(2) statutory damages, as provided by subsection (c).

(b) Actual Damages and Profits. - The copyright owner is entitled to recover the actual damages suffered by him or her as a result of the infringement, and any profits of the infringer that are attributable to the infringement and are not taken into account in computing the actual damages. In establishing the infringer's profits, the copyright owner is required to present proof only of the infringer's gross revenue, and the infringer is required to prove his or her deductible expenses and the elements of profit attributable to factors other than the copyrighted work.

(c) Statutory Damages. -

(1) Except as provided by clause (2) of this subsection, the copyright owner may elect, at any time before final judgment is rendered, to recover, instead of actual damages and profits, an award of statutory damages for all infringements involved in the action, with respect to any one work, for which any one infringer is liable individually, or for which any two or more infringers are liable jointly and severally, in a sum of not less than $750 or more than $30,000 as the court considers just. For the purposes of this subsection, all the parts of a compilation or derivative work constitute one work.

(2) In a case where the copyright owner sustains the burden of proving, and the court finds, that infringement was committed willfully, the court in its discretion may increase the award of statutory damages to a sum of not more than $150,000. In a case where the infringer sustains the burden of proving, and the court finds, that such infringer was not aware and had no reason to believe that his or her acts constituted an infringement of copyright, the court in its discretion may reduce the award of statutory damages to a sum of not less than $200. The court shall remit statutory damages in any case where an infringer believed and had reasonable grounds for believing that his or her use of the copyrighted work was a fair use under section 107, if the infringer was: (i) an employee or agent of a nonprofit educational institution, library, or archives acting within the scope of his or her employment who, or such institution, library, or archives itself, which infringed by reproducing the work in copies or phonorecords; or (ii) a public broadcasting entity which or a person who, as a regular part of the nonprofit activities of a public broadcasting entity (as defined in subsection (g) of section 118) infringed by performing a published nondramatic literary work or by reproducing a transmission program embodying a performance of such a work.

(d) Additional Damages in Certain Cases. - In any case in which the court finds that a defendant proprietor of an establishment who claims as a defense that its activities were exempt under section 110(5) did not have reasonable grounds to believe that its use of a copyrighted work was exempt under such section, the plaintiff shall be entitled to, in addition to any award of damages under this section, an additional award of two times the amount of the license fee that the proprietor of the establishment concerned should have paid the plaintiff for such use during the preceding period of up to 3 years."

I hope this helps, and I hope swift and determined action is taken against any and all violations of this kind.

Finally, a link to a recent example of theft for commercial purposes, this journal entry discusses what took place and who was affected [link] it is from but it concerns all.