Can't say exactly why, but I had this suggested by IDEA (?) as well. Could be because background is a kitchen-sink of everything there is in a background includ

Can't say exactly why, but I had this suggested by IDEA (?) as well. Could be because background is a kitchen-sink of everything there is in a background including several different DSLs for gradients and such. So it makes sense to keep just background-position if there's a simpler background: the browser will spend less time processing it. Whether that is measurable is a different story :)