Really? Overwhelming? Like what?! There's not an awful lot to it and you don't even need to use a lot of the mechanics if you don't want to - I hope your friends aren't pilots or doctors or anything serious!
"If you don't want to" is the key phrase. Most gamers aren't satisfied with being ignorant of mechanics, and ED doesn't provide a lot of feedback for many of the things we do, such as controlling pips, throttle, thrusters, etc.... Being required to do it all at once, and then not getting any direct response as to whether what you did was effective, or even affected anything at all, when you are also being required to immediately shift your attention somewhere else, is frustrating for a lot of people. If they don't feel they are making progress in learning the game, they're not going to bother, because it just feels like a waste of time.
Everyone encounters this with different varieties of games. RTS is my particular bugbear. Unless you can convince me that you enjoy all games and their mechanics equally, in which case I want to see screenshots of your Train Simulator Hours Played.