"read" and "copy link" in post_menu_hidden_items

Continuing the discussion from Post Share now Link Copy Only?:

While I had a look at the post_menu setting, I noticed that not all items in that list are a choice in the post_menu_hidden_items. Is there a reason why “read” and “copy link” are not allowed to be hidden? Since you can, for example, hide “share”, I had the impression someone just forgot to add them.