Sects and spirituality
An authentic spiritual path implies making great demands of oneself, but being very tolerant towards others. In most sects, however, people are very demanding of others, but flagrantly contravene the ideals they profess themselves. It only needs one person with a little bit of charisma who decides to exploit his or her influence, for people to gather around and become mentally and physically enslaved.
The fundamental difference is that sects are either pure fabrications, fraud and deceit, or based on a mishmash of disparate elements borrowing bit of various traditions that have no link to an authentic spiritual transmission and aren't based on any authentic philosophical principle. They therefore can't bring about any durable spiritual progress, and only engender confusion and disillusionment or, even worse, exploitation and suffering.