You're right - the thing about noise is more of power distribution/grouping arrangements... the isolated outputs matter because it allows you more groups and so less "disturbance" to the other pedals (since its isolated).
So its both tech and human...
In my experience though - isolated outputs can cut down on noise... and its quite effective surprisingly. My friends with isolated Power Supplies report on the same thing too...
In other words.
Dude.
PP2+. Musicom. Juicer. T-Rex Fuel Tank Jr.
Hehehehehe.