Frank Zappa put it like this:
The only difference between a cult and a religion is the amount of real estate they own
Compare the advent of the internet to the invention of the printing press: the principle thing that changes is the velocity of myth propagation. The printing press was one of the most important religious "weapons" during the reformation.
All religions started as cults. The main criteria for a cult to survive its early phase and grow into a religion have been studied and identified by antropologists:
Charismatic Authority. This is the emotional bond between a leader and his or her followers. It lends legitimacy to the leader and grants authority to the leader’s actions while at the same time justifying and reinforcing followers’ responses to the leader and/or the leader’s ideas and goals.
Transcendent Belief System. This is the overarching ideology that binds adherents to the group and keeps them behaving according to the group’s rules and norms. It is transcendent because it offers a total explanation of past, present, and future, including the path to salvation.
Systems of Control. This is the network of acknowledged—or visible—regulatory mechanisms that guide the operation of the group. It includes the overt rules, regulations, and procedures that guide and control members’ behavior.
Systems of Influence. This is the network of interactions and social influence that resides in the group’s social relations. This interaction and resultant group culture teach members to adapt their thoughts, attitudes, and behaviors in relation to their new beliefs.
You can check any cult or religion (surviving or extinct), modern or ancient, against this list. The internet is merely a faster carrier used to permeate their specific mythology. It is a means to an end, and though the form(at) may change (like the use of YouTube in stead of text, or agressive use of social media), the goals and messages don't.
So, of course modern cults invent their own myths or tweak/re-interpret existing ones to set them apart and make their group "special" - just like they have done for millenia. It is through the propagation of item 2 in the list that a cult sets itself apart and establishes itself. Without a myth, a cult leader has nothing to fall back on to justify his/her leader position.