This is because the DMCA takedown is a legal process. You file notice that someone is stealing your content, the content gets taken down. The person you filed the complaint against has the ability to counter that claim. If they counter the claim, they can have the content restored. At that point, your option is to to sue the individual.
Contact information for you is required as part of the process.
"There are several elements that should be included in a takedown notice that are specified by the copyright law. If most of these elements are not included, the service provider may refuse to take down the material. Even if a takedown notice meets all the legal requirements, the service provider still may refuse to takedown the material. However, if they fail to do so, then they open themselves up for potential secondary liability for assisting with copyright infringement. (see Safe Harbors for more)
The DMCA takedown process can be used regardless of whether the copyright owner has registered their work with the U.S. Copyright Office. It should not be used for anything other than copyright infringement claims. Many service providers offer easy-to-use online tools to submit claims directly to the provider through an online DMCA takedown form.
After a takedown notice is sent to a service provider, the provider usually notifies the user, subscriber or other person who is responsible for engaging in the infringing activity. If that person – the alleged infringer – in good faith does not think the activity is infringing, he or she can send a counter notice to the service provider explaining why they disagree with the copyright owner. After receiving a counter notice, the service provider is obligated to forward that counter notice to the person who sent the original takedown notice. Once the service provider has received a valid DMCA counter notice they must wait 10-14 days. If the copyright owner sues the alleged infringer in that time frame the material will remain down, but if no suit is filed then the service provider must re-activate or allow access to the alleged infringing activity."
The required information for a DMCA takedown notice is as follows:
(i) the signature of the copyright owner or an authorized agent;
(ii) identification of the copyrighted work claimed to have been infringed, or, if multiple works are on a single site, a representative list of such works;
(iii) identification of the infringing material or activity (or the reference or link to such material) and information reasonably sufficient to permit the OSP to locate the material (or the reference or link);
(iv) contact information for the copyright owner or authorized agent;
(v) a statement that the person sending the notice has a good faith belief that use of the material in the manner complained of is not authorized by the copyright owner, its agent, or the law; and
(vi) a statement that the information in the notice is accurate, and under penalty of perjury, that the person sending the notice is authorized to act on behalf of the copyright owner .
