I'll begin by telling you that there are two kinds of phaser effect: those that are, and those that aren't - nearbeer designs to the smallstone are rare as dodo's because there's only one smallstone - and not just in the real world either.
You can search google and wiki to find precisely why, but artsacoustic have managed to create 'the' version.
Why other companies have transmogrified the notquite design of boss/ibenez phasers is a mystery sort of answered on their website. The main thing is that they've managed to do it where no-one else seems to have even bothered.
Smallstone wasn't the first/original phaser - just the best. And the BigRock for all intents and purposes is also the best: the best vst phaser.
How they arrived at the realisation that there was something needing addressing is as irrelevent as the cause of art. They've succeeded in making a lot of people very happy.
So to this mysterious sound - it's Lush, Rich, Opulent, Shimmering, Chinese Silk, Blueberry Milk, Redolent, Whipped Honey, Vanilla Cream, Porter, Wine, Whiskey, Opal Ruby Emerald Amethyst Sapphire, Oceanic, Rain Forest, Purple Haze, Middle Earth, Rainbows at Night, Hubble Telescope, Apple Blossom, Summer Sunsets, Minor Chords, Morning Snowflakes, Chocolate Coffee, Autumn Mists, Starfields, Golden Syrup on Devilled Ham, Spring Showers, Valley Breeze, Alien Disco, Beef Stroganoff, Orange Juice, Halfsleep, Exotic Holiday, Venus, Saturn, Reflective Lakes, Beautiful Girls, Gotham City, Blade Runner, The King's Banquet, Scotland, Irish Castles, Siberia, Sahara, Australian Outback, Amazon River, Lasagna, Mudcake, Afterdinner Mints, Perfume of the Girl Who Just Left The Room...