You can get a judge to order and injunction for a cease and desist which make it’s legally binding, but it’s not the only method available.
I can send you a cease and desist to stop commenting on my comments, if you don’t I would either than take you to court, or drop it.
A dmca means nothing to the person who did the copyright infringement, great I can’t put the video on YouTube, on to the next one… how inconvenient and obstructive to their work.
You realize you’re on the fediverse where anyone can Self host instances… yeah?