The best way to "prove" that modern day Jehovah's Witnesses aren't really about the purity and soundness of the teaching is the fact that no counter movement has sprung up as a successful schism in any manner other than a loose federation of complainers on the Internet.
Religion just in America is full of spin-offs due to doctrinal disputes.
The Mormon Church is quite iconic and yet it has a Reformed Branch.
They are pretty darned recent, but, Jehovah's Witnesses are even more so. All there schisms took place after the death of Russell.
No--it isn't the purity of teaching or the false prophecy bugaboo that fuels this religious cult.
You want to know what I think holds it together?
It is narrow and oppressive.
Dumb people need to be told what the world is about in a black and white fairy story. Then, something has to be demanded of believers and enforced with lots of pressure, threats and scary consequences.
Rational thinking is hard work and a lonely one as well.
With hardcore Authoritarianism you get to run in a pack and no thinking is required of an individual nature.
Groupthink, lockstep behavior, promised rewards ("soon") and lots of scary consequences.............
That's what JW's are all about.