Lately, chipmakers have been popping out pieces with crazy amounts of cores, all the way to deca-Core. MediaTek and Samsung have both put out flagship octa-core chips. Even Qualcomm has gotten in on the action, making this declaration seem a bit off-base, or perhaps a realization after the octa-core Snapdragon 810 had such a chilly reception and bad reputation due to its heat issues, which were no doubt linked to having so many cores packed into such a tiny space.
With the Snapdragon 820, Qualcomm has apparently made good on their word. The new powerhouse of a chip sports only four custom Kyro cores, two of which sport incredible performance and two of which are more apt with battery conservation while still providing ample power for the basics. Qualcomm says they feel forced to release octa-core chips and even crazier configurations because consumers would shun them otherwise, fooled by other chip makers' slick marketing into thinking that more cores is more power. Qualcomm posits that instead, chips should have their mettle measured by per-core performance and LTE throughput, since data transfer rates can have such a huge effect on user experience these days. From web browsing to streaming and most web-enabled apps, it can be pretty easy to confuse a slow connection for your phone itself lagging behind. Qualcomm also stated that, in a nutshell, Android apps currently aren't optimized to use more than two cores, for the most part. This leads to a complete waste of most of a chip's power, if it relies on tons of cores. For some advanced apps and heavy games, this may not be true, but you can be certain that full core optimization is not a requirement to build apps for Android.
Qualcomm put the declaration rather dismissively, basically leaving it at that rather than providing facts and figures to back up their bold claims. The best benchmark us consumers have is simply waiting for the Snapdragon 820 powered handsets to hit the market and pitting them against octa-core and more flagships, powered by great crazy-core chips like Samsung's newest Exynos, Mediatek's powerful and low-cost Helio 820 and Huawei's behemoth Kirin 950.