Well it does seem to me that there isn't a lot of logic in all this. I don't lie awake at night worrying about it but, for example, audio meters are not under this menu but under a different one, and unl**** FX bins they have two commands - Horizontal and Vertical. Since these are mutually exclusive, I don't see the logic in this.
I suspect that what has happened is that over the years as more features have been added, these menus have sort of expanded more or less on an ad hoc basis. That's fine though.