Why are smartphone chips suddenly including an AI processor?

If virtual assistants have been the breakthrough technology in this year's smartphone software, then the AI processor is surely the equivalent on the hardware side. Apple has taken to calling its latest SoC the A11 Bionic on account of its new AI "Neural Engine". Huawei's latest Kirin 970 boasts a dedicated Neural Processing Unit (NPU) and is billing its upcoming Mate 10 as a "real AI phone". Samsung's next Exynos SoC is rumored to feature a dedicated AI chip too. Qualcomm has actually been ahead of the curve since opening up the Hexagon DSP (digital signal processor) inside its Snapdragon flagships to heterogeneous compute and neural networking SDKs a couple of generations ago.