No, no, I can't take the credit for that lmao..the "catch action" have always been something SMF devs built in early on(and luckily kept so far) so that you could "run" a custom action within a theme just by supplying a template with the same name as the action + setting the $settings['catch_action'] variable with the layers you will use. I only worked a bit further with that and used it over the years to run custom pages within themes from a folder called "pages" in each theme.
As for the menu positioning, its just something I made to be able to stay away from using a mod to jumble the menu items. As it saves only the positions of the menus - not the menus itself - its not taking much space. Its also saved in theme settings table, so its cached along with the rest. Your own custom menu items of course require some space, but again just title,url and position doesn't take too much of that either.