When this volume first appeared, it served as a one-stop, one volume compendium of current "new religious movements" and the "peculiar prophets" who propagated their teachings, especially in North America, Canada, and Europe.
With the advent of the Internet/social media platforms, there are websites which perform the same tasks that this particular book has, especially when it comes to/came to the (all inclusive rather than mutually exclusive) nature of the New Age.