They are called "system on a chip" for a reason - mobile phones don't have discrete components but CPU, GPU, ISP, etc. are all packed into one. There's not much choice, if you want to go from an AT tower PC to a pocketable super gadget. Sometimes you can have your cake and eat it too. The big.LITTLE type processors give you the performance of big cores and the power efficiency of small ones. Basically all mobile chipsets use this multi-tiered setup (usually two clusters, but sometimes more). Specialized processors have done some great things - Google's Visual Core in the Pixel 2 sped up...
Source: https://www.gsmarena.com/weekly_poll_lets_build_the_best_chipset_ever-news-29234.php
