The "Cytherians" was another one of those enormous technology infusions for Starfleet that went nowhere. Given all they learned about how space could be warped and take the Enterprise across vast distances in practically no time, you'd think that this would be quickly adopted. But no, it was forgotten never to appear again.
Well, if the Cytherans were
related to the ST5 God, they would have had the ability to make seemingly reasonable people believe impossible and silly things, and forget all about other things that made perfect sense. The heroes would definitely not have left the center of the galaxy with all of their marbles...