I'm not sure of the reasons for it, but in AE to say "serves us (or me, him, them, etc.)" and then add the direct object is completely acceptable, but doing the same for "explains" is not. After the word "explains" you need to put the direct object (what is being explained), and then add "to us (me, him, etc.)" at the end. This is about correct English, not a quirk of DL.