They don't think so. Some claims that they were born with the wrong body, so their deadname was a mistake. This is why they call it deadname.

Even if you are not transgender, just imagine changing your name, telling everyone about it, and someone would come along insisting on calling you using your former name, practicly mocking, belittling you and your choice. Now imagine them doing the same to your entire identity.

Similarly, a woman who exits a bitter and acrimonious divorce may change her name back to her maiden name, and hates it when people refer to her as "Mrs. Ex-Name".

Or a daughter who dislikes her father so much that, upon reaching adulthood, changes her surname because she wants to be completely disassociated from him. (In the case I'm thinking of, she said something along the lines "he wasn't my father, he was the sperm donor" - he left when she was a few years old.)

Personally, I understood the idea first through Malcolm X, who rejected "the white slavemaster name of 'Little'" he was given at birth. And the respect Howard Cosell had to refer to Muhammad Ali by Ali's chosen name, while most others used and even taunted him with his old one.

Same ghost, different machine. Their identity is now Eliot. Probably wouldn't even be an issue to call them Ellen if we lived in a world where people weren't deliberate with their mis-identification to troll trans people, but here we are.

If I change my name from John to Jack and people keep calling me John, I'm probably going to be annoyed. Moreso if they're clearly doing it to try and get under my skin.