Wipika had other problems with their kites around this time, not just delamination. Larger size Mylar Wipika kites were prone to blowout along the leading edge. Polyant's contention that Mylar could not handle the physical demands of kite design was largely correct.
Excuse me but I can't agree with you. Some mylarized Classic and Airblast are still flying (read the posts), so Polyant's contention was wrong.
All problems were linked to delamination. A laminated composit gets its cohesion from the 3 components, fabric, glue and mylar. If the cohesion is lost, for sure the seams will go apart.
I saw at that time some brand new kites coming direct from the factory with some LE panels already FULLY delaminated, what means that Polyant and LAM didn't give a shit on what they delivered to their customers.
On a Dacron the cohesion comes from the high "density" of the weaving, the thermical treatment (if done) and the coating. We got some troubles at Takoon with LE seams going apart due to a defective Dacron coating. You will certainly remember it too.
Sure that for the larger kites, it would have been better to design a heavier mylar fabric but the needs for such composit were not large enough yet.
The shift to the Dacron was in large part due to the fact that customers associated Mylar to Delamination, so a radical change was required.
The kitesurf industry has since then undergone several major suppliers' failures such as the caps that didn't weld well. The reason is just that the main supplier slightly modified the chimics of the plastic without warning its customers.
Is the kite industry responsible for not checking enough its products ? Maybe partly but such disasters also happen in car and sailboat industries for example (polyester osmosis)