Reality is also hard and that's why people aim to reach it. Making alien world is easy because the viewer has no reference point, so you can go banana with it.
You can't capture psychedelic and or mystic experiences, which are very subjective anyway and yes, rooted in _reality_ or require a reference to _reality_ as they are the so far away from that.
Do you believe that there were no genres of music born in the 20th century, or that we conveniently discovered all the genres just a few decades ago? Neither of those seems reasonable to me.