Question on Morley volume in loop

[Justus]

So I've been looking at volume pedals.  I like the features of the Morley PVO+ (volume plus) but have read that it is not meant to go in an effects loop like the Little Alligator volume pedal, but instead is supposed to go in front of the amp.  I don't understand that.  What would make it that way?


I'd like a volume pedal after all my OD/preamp and before mod/delay, so I thought early in the effects loop would be a perfect place.