Really.. Again.
It 2016 folks. Games are online.
Sorry, this is blatantly untrue. There have been a few attempts at a mandatory online DRM (the most notable being the first iteration of Ubisoft's Uplay service and Microsoft's original plans for the Xbox One console), but these have failed, largely due to gamers basically telling the companies trying it where they can stick their games. As a result, virtually any game in existence that actually has a single-player mode can be played offline without any problem at all. Some of these games do have online features, even for the single-player, but all that happens is that these features are unavailable if you play offline - the core game can still be played no problem.
However, having said that, ED is something of an exception - it is the case that the game, as it currently is, requires internet connectivity to work. Now, there may be a legitimate argument in saying that the developers should have made the game differently, or that they should create a different mode that functions differently, so that the game can be made to work offline, but that is different from saying that the only reason it is online is DRM, which is simply not the case.