I noticed that difficulty settings are only present when setting up a private match. Why are there no difficulty settings on public matches like there are for Arcade Mode?
As I do not have any mates who play Gears regularly, its going to be almost impossible to get the medal "For the Horde! – Complete all 50 waves of Horde on Casual, Normal, Hardcore, and Insane." as I won't be able to set up 'Private' matches.
Best Answer
Unfortunately, there is no answer for this as it would require one of the game designers to come in and submit the answer for us.
However, upon looking at all three games in the series it can be noted that there are many achievements that can only be obtained by playing online with other players. You can draw your own conclusions as to why that may be, but suffice it to say in here: that's just the way it is.