It's a doubt I have since when I started listening to electronic music. In my head, electronic music is created like this, i.e. sitting at a computer in a comfortable room. There is no real time performing, just a lot of time to spend composing and letting the computer process what you composed.
So what do electronic music producers do at a live concert? I can imagine them playing the main melody on a keyboard or a particular beat on a pad, but there are way more effects and sounds in the average song that what is possible to reproduce with just two hands.