Cults fill important human needs for human connection, structure, seemingly-legitimate authority, existential meaning and a driving purpose for life. To the degree these aren't provided by healthier structures in our society, individuals will be drawn to these organizations. And many things which we do not often think of as cults in many ways fit into the broader conception thereof: militaries, political parties, yoga studios, etc. have all been known to fall into that classification.

Steve Hasan's BITE model is a great framework for thinking about these things. In many ways, control of behavior, information, thoughts, and emotions is what all human organizations do, so it's more of a cost/benefit analysis than an either/or analysis that's called for. There are varying degrees of "cultiness". Recommended reading: "Combating Cult Mind Control".

An evolutionary analysis of these sorts of social structures is also fascinating. If you treat a cult like a superorganism that must compete for resources with other organizations in the culture, you can understand many of the pressures driving them. Jonathan Haidt has shown how "morality binds and blinds", and this is nowhere stronger than in cults whose distinct moral code both binds people together into a unit, and blinds them to the true nature of the group.