That had little to do with it. The fact is when iPad first came out here where mannerly adopters on a devices that wasn't exactly there yet. it literally took a few revisions to get to the point where performance justified holding onto the device for more than two generations. Now we are seeing a hardware releases that is compelling thus driving sales above the base level for iPads. Once the upgrades are done sales will slip back down a bit. It simply is the way of tech gadgets.
The A8 and A8X processor in the mini 4 and Air 2 were not compelling in 2014 and 2015? Those tablets had a laminated display and 2GB RAM.
Yet a rehashed 9.7" iPad using an old A9 with 2GB RAM and non-laminated display is suddenly compelling for 2017?
Let's be honest. Apple ditched the iPad mini and focused on making cheaper 9.7" iPads. People wanted cheap 9.7" tablets, not an expensive mini 4 or Air 2. The financial results today speak for themselves.