Dr. Martin Luther King wrote and delivered his famous “I Have a Dream” speech more than fifty years ago. When he obtained copyright protection on the speech in 1963... the copyright on the “I Have a Dream” speech will not expire until the end of 2058. Because the Estate of Martin Luther King, Jr., Inc. and its affili- ates have closely guarded the speech in a copyright enforcement and li- censing sense, the public seldom sees more than snippets of one of the most highly regarded speeches in history.
https://ir.lawnet.fordham.edu/iplj/vol25/iss4/2/
And there are many more examples like this. Copyright was supposed to foster creativity and the distribution of knowledge. Know it's used to stifle competition, and to protect corporate interests.