Blizzard did not make a “mistake” they did not force move the player without announcement nor accidentally destroying their toon etc. Should the player eventually not choose an option, a random realm choice may be picked though.
According the realm list here since you’ve missed it:
Each realm that has an option to move to Firemaw, essentially has 2 other options too. The delivery party refers to moving a toon from A to B wholly.
I don’t understand this, the server has moved from Classic Era, to TBC, to Wrath and now will to Cataclysm that should suprise no one yet people keep being weirded out at it each expansion…? This literally happened at Retail, every expansion.
No one screamed to keep Shadowlands only realms when we moved to Dragonflight.
Or the players wanted to play something else. Like HC after SOD got launched that. Or Plunderstorm. Or anything else really. Their time and money, their choice.