I agree that all speakers can be made to disappear with proper placement of the speakers and the listening position. It also MAY help to have some room treatment (can be as simple and unobtrusive as putting up a wall hanging on large exposed surfaces or adding diffusion with bookcases, potted plants, etc.).
The difference between speakers tend to make certain types easier to get to disappear. Small standmounted speakers placed well away from walls are particularly easy to make disappear.
But anything can be made to disappear. Just this weekend I heard a system with very good imaging that sort of defies the usual expectations because of its size. It is more than 30" wide, taller than six feet and is three feet deep (horn-based). If that elephant in the room can disappear, anything can.