As in why is there a publication ban on a person's name (Dick Levine, Thomas Schneider etc.) before they converted to the trans religion? When non-Muslims convert to Islam and take a Muslim name, there's still a record of their birth name. Everyone knows that Kareem Abdul-Jabbar was once called Lew Alcindor. Everyone knows that Muhammad Ali was Cassius Clay. But not everyone knows that "Rachel" was (well, is) a Dick. And those who do know are not allowed to say so. Nowhere else is writing "AKA" or "né/née" considered a "hate crime."
When someone converts to the trans religion, they get to change their birth certificate, and actually punish people for even so much as mentioning that other name. People change their name in court all the time, or go by pseudonyms (like stage names, for example) but only the trans religion basically demands that the whole of society sign an NDA.
And why call it "dead naming"? You're not allowed to say the names of dead people? Well, that would put the headstone industry out of business. If this bizarre standard was implemented elsewhere, it would make Reggie Dwight doubly culpable for writing a song that starts, "Goodbye, Norma Jean." Because Marilyn Monroe is dead and also, that's not her given name.
What is the point of this? Do they think that their other "self" is going to be invoked like an evil spirit or something if you say "Beetle-Bruce, Beetle-Bruce, Beetle-Bruce"?
Honestly, I think for some of them, "transitioning" is like a soft way of committing suicide. They attempt to obliterate the person they were and are, and replace that person with a new character they invent, with a fantasy of who they'd like to be. So they have a very negative response to anything tying them to their past, to that person they hate and don't want to be, to past actions they regret (or that they refuse to take responsibility for). Using their given name does that, and it shows that people who knew them before still see them as who they were in some ways. They don't want that continuity.