The Monk knows more than myself about this, but I'll tell you what I know.
Polyvinyl Alcohol (correct short form is PVOH) has been around since before WW2. It was formed into all sorts of cloths and threads, certainly nets too.
By the way, PVA is the short form for Polyvinyl Acetate which is used in paints, hence PVA paints and coatings. It is NOT the correct short form for the stuff that dissolves.
One of the uses for PVOH was to wrap up floatation and life saving devices so that when they were in contact with water, the thread would dissolve.
As in many things, there is very little that is new in angling.