Root blame is probably Telstra doing some corrupt dealings with the Liberals so they could sell their copper network to nbn co.
nbn co never would have needed to buy the copper network if they were simply replacing it entirely.
I worked in the service activations and assurance side of nbn co right when FTTN was starting to roll out. Install issues suddenly stopped being "delayed because no one was home" or "lead-in conduit needs replacing" and suddenly had about a dozen different reasons.
For the entire time I worked there, fault volumes for the FTTN network were consistently 10x worse than FTTP. For example, there might be 0.02 faults per 100 active FTTP premises, and 0.2 faults per 100 active FTTN premises.
Edit: though with some more thought on the original point, I think it was majority just the Liberals wanting to do something different in classic oppositional politics.