The problem with a cult is actually the members who agree to abide by and enforce their rules. In the JW world, it's not the Governing Body that makes the membership grow, but the die-hard deep-in members who make the local congregation flourish.
A cult has power, not because of the leaders, but the followers. Many JW's voluntarily subscribed to their shunning policy when getting baptized, without getting mentally prepared to face the shunning themselves.
In my life as a JW, I chose to become a JW (no one forced me), and I played an active part in enforcing their shunning policy for many years. I felt it was right, however, when I became the shunned one, the reality dawned on me.
Rather than blaming the WT, it's just that I am reaping the results of my choices, and facing the same behavior that I did to others. Maybe it's even now.
JW's are not a cult. Their followers have made it one.