You’re cherry-picking (not very well), to create a result that supports your argument. The 2017 MacBook Pro has a 5w TDP CPU in it, not a 45w TDP CPU and is running at 50% the clock speed and yet the difference between the two in single-core is less than 2%, which is frankly amazing to see just five years later.
One the other hand, if you compare the 2016 MacBook Pro at 2.7GHz ($2799 16GB/512/RADEON 455) to the 2012 MacBook Pro at 2.7GHz ($2999 16GB/512/GT650M), the single core is 4624(2016) versus 3614(2012) and the multi-core is 15552(2016) versus 12011(2012), which shows a 28% (SC) and 30% (MC), 2016 Flash Storage speeds that are 8x-10x faster than the 2012 and a GPU score that is more than 3x faster.
While the 2017 MacBook can’t compete with the 2012 MacBook Pro (Retina) in multicore, that’s a trade off people are willing to accept to have a 12” form-factor versus lugging a 15” portable. At this point, that’s really all you’re giving up with the MacBook as the single-core gap is neglible, while getting jsut as much DRAM, flash storage that is 5x faster and an integrated GPU that is just about as fast as the discrete GT650M (at least in a synthetic benchmark).
Extending hardware support is nice and all, but I suspect most of Apple’s suppliers aren’t even making the raw components anymore (CPU, GPU and flash storage) that Apple would need to continue supporting these computers for another 4 years. I love my 2012 2.6GHz and it still functions well, despite the well documented issues that Apple has had with this model. I bought a refurbished model through Apple’s online store and it has been my main machine for many years, but looking at how much technology has advanced since this laptop was released (GPU and CPU power increases, flash storage speed, display, Thunderbolt bandwidth), Apple can’t simply stockpile minor parts, motherboards, batteries, et al. to have on hand hoping that someone will want replace an 8-10 year old motherboard or battery when it dies, no matter what it would end up costing. It’s simply not cost effective for any business to stock parts for that long, especially a high tech hardware manufacturer. Why would I want to spend $800-$1,000.00 on a motherboard and a battery for a 2012 computer when I can get an up to date model? Especially with laptops, where most everything is soldered down anyways...desktops are certainly a different discussion altogther.