But festivals like this are dedicated to music which is definitely is not everyone affair: most people just don't like it. If you want to judge for yourself, the festival in question had artists like Psykovsky and Fungus Funk. Do you think that this is something general public would enjoy listening? (No elitism intended, I don't think that my music taste is better than anyone else's. I just as a matter of fact know that it's a little different).
But if you're one of the people who like and follow this music scene, you'd probably go to some publicly announced psytrance parties, meet people there, and hear about this festival as well.
And finally, there's question of the authorities. Even if we forget about the very strong psychedelic tradition that follows this genre of music (it's literally in the name, and for a very good reason), it's not a good idea to draw attention to any music event in Russia, unless you have very good lawyers and serious money involved that can protect your interest.