This only matters from a long term reliability and overclocking point of view. For chips operating at stock performance they will still perform as good as identically.
If a chip is sold as an I9 9900K then it will perform like all other I9 9900K in stock operation. It might be a bad bin so have 0 overclocking headroom and fail in 5 years or a good one which can reach 5.2 GHz and last 15+ years. However both of them will still achieve as good as the exact same framerate in HotS or any game for that matter.
I think you might also be getting confused with yield based product separation. Some standard chip designs are binned during production and separated into different products based on the binning result, with better bins fetching more. This is best seen with the AMD Ryzen 7 3700X and AMD Ryzen 7 3800X. Both of these use the same pieces of silicon except that binning is used and all the high end dies end up in the AMD Ryzen 7 3800X while all the low end ones with defects end up in the AMD Ryzen 7 3700X. No AMD Ryzen 7 3700X will perform as well as the AMD Ryzen 7 3800X as a result, despite during manufacture the die having the potential to end up as either before it was binned. However this also proves my argument since as a normal gamer there is no reason to spend more money and buy the AMD Ryzen 7 3800X since the AMD Ryzen 7 3700X performs very close in gaming workloads.
My I7 920 lasted ~10 years. Only reason I am getting a Ryzen 9 3900X as a replacement (and having to use the other system until then) is because a PSU fried either the motherboard or the CPU and it was not worth replacing like for like with something 10 years old.
It is perfectly reasonable to consider supporting 10 year old hardware. Especially if the game has not added anything significant since then that justifies the need for more powerful or modern hardware. This is especially important for keeping target audience large since people in developing countries can only really afford 5-10 year old hardware.
Which is exactly what many modern Mac systems are doing, not hindering you. The new iPad pro would run HotS acceptably, certainly at 30+ FPS I would imagine. The main concern is to make sure that the player is using a keyboard and mouse, as the game was designed for. Playing with a track pad or touch screen will not result in a high skill experience. However maybe match making will cancel this out since it is unlikely they will reach higher skill MMR with such a handicap.
macOS (OSX) is only for x86. IOS is only for phones and then there is their tablet OS. Within the product stack and supported devices the same OS version is used. It is only devices that fall out of support keep using old versions of the operating system, and such devices are usually unsupported by game developers anyway. This is not an argument of if Mac products are value for money, rather that the new ones are capable for running games like HotS, including their flagship tablet and possibly even phone.
The same could be said about Windows 10. Every major release brings new APIs and might change existing ones.