Biggest reason is to help spread the load. It helps reduce the point load on any one fastener. If this is just hanging a couple of thing or making a shelf, no big deal. I guess I inferred, possibly wrongly, from your first post that you were to be suspending pipes. That made me think of potential load bearing issues when coupled to a CMU wall. Like I said I may be over cautious on some things, given my background doing installs of grids, So ignore me if I'm overboard, on this one.
