Essentially they are time rifts and the quests to get the time rifts in zones feel a bit bland and unrewarding. Just go here and collect... I'd like it if they served as a sort of flashback where upon activation we see the past history of the zone to serve as a method of learning it's lore, similar to how the memory stonee quest in vvardenfell lets you see past memories of a family. Imagine going and doing time rifts in deshaan and seeing nerevar at his prime with almalexia or going to locate time rifts in skyrim and seeing memories of the dragon cult