Mailable and Multiple Update

You're right.

We build the mailable lists to define which items could be mailable, avoiding to set up this feature for parameters screen.
When we set the Multi-update feature, we had to define same kind of list and before creating a multiupdatable list we realized that is would be exactly the same as mailable list, and there was no reason it coul differ. So we used same list (and then same condition)