Because Destiny Says So: In some cases, played straight due to the tendency of the Transcend (and other potential acausal-logic using seed AIs) to whisper in their own ears from the future; however, while they do apparently intervene in people’s timelines for the sake of their Optimal Futures, a combination of the even-if-you-could-formulate-the-right-question-you-couldn’t-understand-the-answer effect and the nature of predestination paradoxes means… well, good luck getting anything out of them on the topic beyond “Further information is not available at this when-where,” Chosen One or not.

(Averted in mythology.  Laryssan, eikone of fate and destiny, is portrayed as asleep – and voluntarily so, in order to spare the universe the chains of absolute predestination that would result if she was actually awake and thus aware of all the possible links of cause to consequence throughout time.  How much influence the dreams of Laryssan had was something of a matter of theological debate back in the day.)