The edges of the bounding box are not geometry. IF the component’s origin is located at a corner of the bounding box, you get an inference point but the origin is not required to be there. The origin is the insertion point of the component. When you bring in an instance of a component from the Component’s window, you will have hold of it by its origin. If you aren’t deliberate about where you place the axes and origin, they will, be default, be located at the lower front left of the component’s bounding box. There are many cases where that isn’t the logical point to grab the component for insertion but that is up to you.
For components you get from the warehouse, you should check to see where the author left the origin. Does that make sense for how you’ll use it? If not, move it to where it should be. Frankly, with chairs like those in your screen grabs, I would place the origin at the center on the ground. But that’s just me.
Here are a couple of examples in which I centered the origins on components to make them easier to place.
I centered the origin of the glass components on the bottom of the glass so I could quickly drop them into the holes in the tray and know they are center.
I did the same sort of thing for the knob component on this bench. Then it was dead easy to drop the knobs on the centers of the drawer front.