All these comparisons are all great and that,but it is always mobile chips in their most optimal environment against desktop chips in a lesser one.
Apple has a very wide and low clockspeed core,running its own custom OS using its own tweaks. The Intel and AMD CPUs are designed to scale to much higher clockspeeds and are running a range of OSes.
Its not really a fair comparison - you ideally need to run all the chips under one environment.
Just scaling to higher clockspeeds is not easy - compare Jaguar and Piledriver(similar single threaded IPC),or various IBM Power designs and Apple is relying on jumping to new nodes early to get these performance jumps.
CPUs need to be designed to hit higher clockspeeds in the first place. You can't just expect a low frequency design to suddenly hit higher clockspeeds,or suddenly a design which scales to a few watts,to suddenly be able to scale upwards to higher TDP classes.
Then just because a dual core CPU looks great in a narrow range of tests,you can't suddenly expect it to scale well upto 8 cores or 16 cores without any major issues on the way.
AMD and Intel have had to stay on older nodes and optimise from there,and the way things are going shrinks are getting harder and harder. So what happens if Apple hits the issue of not being able to suddenly have a nice new node,and has to make do with an older one??
Also look at how huge the A12 is - 88MM2 for a dual core CPU with integrated graphics on the latest TSMC 7NM process. Look at the 6 core Intel Core i7 CPUs running upto 5GHZ - they are 149MM on a less dense process and probably having far less transistors.
The amount of transistors Apple is throwing at this is huge. The A12 is 6.9 billion transistors - the Ryzen 4 core APUs and 8 core CPUs are under 5 billion transistors.
Plus the Intel and AMD CPUs are more general purpose - I would like to see how the Apple core would fare,if it were designed to run at 4GHZ~5GHZ on a less optimal process node,running more complex operations like video encoding,rendering,etc or even very complex gaming workloads at max IQ. Then use that under Windows.
But the thing is since phones and tablets bring lots of clicks,the whole tech press has to overhype everything like its the next coming of Jebus.
Plus even when it comes to core performance,most of the world's population is running not even the latest and greatest Android devices,or even the fastest Windows PCs.
Is clicking on the Amazon app to buy some trainers suddenly going to be realistically any different between a 3 year old iPhone and the latest one,or some £250 Android one??
All this performance in a phone is great,but its really only a marketing point to justify the premium price,and sounds like the megapixel war with dSLRs and compacts.
This is why people are keeping phones longer and longer - its happening with laptops,desktops,etc.