I suppose it depends on what you mean by “diverse”, most of these groups were quite small, the only gnostic group that seems to have had much widespread success were the Manicheans. The beliefs were certainly out there, that is undeniable, however early on the only major systems seem to be the orthodox, the arien, and the manichean possitions, with the Manicheans playing the role of a master syncratic religion, taking bits and pieces of everything it came across.
Other than Valentius I am not aware of anyone who claimed to have taken their knowledge from the apostles, and as I already said, Valentius was orthodox until he failed in the election at which time he began preaching a hidden knowledge. The circumstances seem more like vanity to me. He certainly was the deciple of a deciple, but that doesn’t prevent error.
You can follow a group that democraticly decides what happened and what did not, but that seems unacademic to me, otherwise one is forced to admit that eugenics is correct, since at one time it had the following of the majority of scientists. Of course that vote has since changed, what does that tell you about democracizing facts?