Mods and admins need to be able to see everything that went down. As it is, you wouldn't know any children comments were removed at all, all the replies just disappear without a trace in the UI.
Beyond that, removing entire comment threads just because a parent comment upthread was removed is really harsh for users. That probably shouldn't be the default behavior, deleted comments should probably show up as [deleted] with their replies still shown and able to be interacted with as normal.
Mods and admins need to be able to see everything that went down. As it is, you wouldn't know any children comments were removed at all, all the replies just disappear without a trace in the UI.
Beyond that, removing entire comment threads just because a parent comment upthread was removed is really harsh for users. That probably shouldn't be the default behavior, deleted comments should probably show up as [deleted] with their replies still shown and able to be interacted with as normal.