It seems to me that only a few groups get the label "cultish", so its not like people put the label on any group with an apparent leader. Such selective labels probably contain a lot of info, so it seems worth figuring out just what that info is. It is not wise to just find one group that gets the label which you think is fine, and then decide to ignore the label.

The straightforward approach would be to collect a dataset of groups, described by various characteristics, including how often folks call them "cultish." Then one would be in a position to figure out what this label actually indicates about a group.