Uncharted Golden Abyss turns off network features during gameplay in order to switch resources to other processes it has been revealed, Shuhei Yoshida has confirmed that developers can pick and choose features as they see fit in order to make the best games they possibly can. He was asked why certain features weren't available:
"To conserve power. When a game wants to push PS Vita's HW performance, it asks to make choices of functions. As PS Vita has many functions, a game can choose diff combination or level of usage within power consumption budget."
Developers can also choose to block the screenshot function at any point to protect the internet from spoilers.