It's a combination of things. Primarily, it's part of the "House Style" or "House Design" to have the off-site links not in the main body, but to list them in

It's a combination of things. Primarily, it's part of the "House Style" or "House Design" to have the off-site links not in the main body, but to list them in a separate box so that people know they are taking you somewhere else, and an appropriate warning given. Without that warning people complain. Really, they do.