I agree, some tracks might be a bit tricky, but still ... Both Zik and Polyphonia make rather non-melodic psytrance around 150 bpm, so it's not really a problem beatmatching it. But Polyphonia seems to like snare-kick-snare-kick, instead of the usual kick-snare-kick-snare routine. That's kinda confusing at times.
You are right though, mixing at lenght is not as important for psy as for other genres. I understand with melodic psytrance, in most of the cases it sounds rather shitty when you mix two melodies that are out of key due to pitch change, but when it comes to the dark stuff it's a different story, layering two tracks from that genre for 2-3 minutes is not that messy at all.
The reason why most psy people think that fade mixing is ok is perhaps due to Goa Gill? He is the first psy/goa dj a lot of people heard about, so he might have set the standard there. As when it comes to other genres, people heard djs beatmixing and often adding effects or a third deck. Just a thought ...