DJing has a quite smooth learning curve, with easy entry point, and one can quickly become passable.
However to build an active following on Twitch is still quite hard work. Maybe not difficult, but certainly seems like it requires persistence and constantly being in entertainment mode. Many put in considerable effort in the "show" aspect of it - on top of the music. Both in terms of visuals and of crowd interaction. I believe that may of those that are successful in the "DJ" format on Twitch would also be successful another formats (like gaming). There are reasons why people choose Twitch DJ over a pre recorded mix on YouTube/Mixcloud/Spotify etc. All this to say that the streamer does bring something. I don't really know how that should be represented financially though...