The 'leaky homes' issue came about because building standards and permits lacked sufficient detail to ensure they used suitable materials in a weather durable manner. Roll forward a few decades and the Councils have had a severe reaming through the courts so they have reacted by requiring building consents to read like a detailed shopping list of permitted building materials and practices. It is no wonder that the suppliers of all of those permitted materials have construed the situation as an opportunity to corner the market. That's how the modern marketplace works.
Gib is just one such permitted material on any building consent but due to it being a major input into most construction projects it has now become the identified bottleneck in the building industry. There will be many more but in most cases the item can be substituted (or its supply deayed) more readily than this integral panelling.
Hopefully the 'powers that be' conduct an inquiry that sees beyond just the opportunism of Fletchers and observe that the NZ construction industry model is broken and the current interventionism is being widely abused by many other suppliers.
This post should have been broken into more digestible paragraphs but the website is fucking with my formatting 