I seem to recall the WT years back about whether or not witnesses are a cult. There was some dark, demonic figure on an article page along with piss-poor definitions of a cult. Then of course, flash-forward to pages of happy, cheery witlesses going door to door. The reader was then left to decide after reading that they clearly weren't a cult.
You won't find a single corporation, business, company who would purposely put themselves in a negative light by defining themselves as a cult, pyramid scheme, etc. Thats like Ford admitting the Pinto was a shit car (which it was). The sales brochure just happened to gloss-over the poor engineering design of the fuel tank placement and instead laid a nice fresh red herring down instead to draw the readers attention to its "compact, efficient" use of storage and "economy" gas mileage.
Therefore, you need third-party groups to offer an unbiased opine about car X, brand Y, or religion Z. Which is why we have things like Consumer reports, Amazon book reviews, etc.
Any religion/company/whatever that hands out a biased, one-sided report about the definition of their existence and then expects the public to adhere to that definition....come on.