No.
During my involvement with The Way International my parents considered "deprogramming" me in order to "free" me from my supposed mental imprisonment. They went so far as to consult with a deprogrammer, who actually talked them out of the attempt, pointing out that failure would mean that I'd likely never want to have anything to do with them ever again. They chose not to risk it. Mom and Dad never spoke of it, but many years later one of my sisters spilled the beans. At the time there was a lot of media focus on cults in the wake of the forced mass suicide at The People's Temple in Guyana. Parents whose children were in cults assumed that all cults were potentially going to end up like Jim Jones' followers. The cults that attracted the most attention also tended to have beliefs or practices (or both) that were far enough outside the mainstream as to appear "weird". The assumption was that the only reason that anyone would get involved in a cult was that they were brainwashed. Mind control was the only way to explain it.
Family members often point to how their loved ones "changed" after getting involved with a cult, not only their beliefs, but their behaviors and loyalties. But is that so unusual when new recruits to a cult are more likely to be young and actually looking to change their lives? Many people who have had family members join the military, especially those who have seen combat, could attest to the changes in the outlook of their loved ones. A new cult member typically is looking for some meaning in their life and a cult provides that meaning. Is it any wonder that they are often exceedingly gung-ho about their new life's focus?
What about when the honeymoon period of cult involvement has ended and the cult member begins to experience some of the abusive treatment? Surely that's brainwashing? Not so fast! We can compare someone who stays in a harmful cult to someone who stays with an abusive spouse, sure that she loves the man who beats her every day, or is afraid that she won't be able to survive on her own. Or someone who hates their job but won't look for a new one. Justified or not, logical or not, people continue in harmful situations either because they fear that the alternative is worse, or have made the calculation that the perceived benefits outweighs the downside. I personally have done both - I stayed in a marriage that was mentally abusive because I was afraid that I'd lose my children and afraid to be perceived as a failure, rather than get out; I continued in a job that was terrible on many, many levels because I judged that the financial benefits outweighed the negatives that I had to endure.
People join cults because they make a decision to get involved in something that they believe gives them what they want...whatever that may be. People stay involved in cults because they make a decision that staying in is the better alternative to getting out. Are they making the "right" decision? Who knows? Unless one knows all the variables in another's life, how can you decide what is best for that person? Spoiler alert: you can't.
So what about deprogramming? You don't hear too much about deprogramming these days, or cults for that matter. But back in the eighties there were a lot of people making big money from the families of young people involved in cults. I know of several people who were the target of deprogrammers, some succumbed and left their cult, some escaped the deprogrammers and went back. What did deprogrammers actually do? Their first step was kidnapping the target of the deprogramming. Kidnapping! Often violently. The head deprogrammer would hire muscle to abduct the target who then be locked away from the world, often in an isolated farm house of hotel room. The abductee didn't usually even know what city they were in. They were allowed no contact with their fellow cult members, were not allowed to leave and sometimes were physically restrained. In extreme cases they were sleep deprived. Various methods of persuasion were employed - the cult's beliefs were questioned or mocked, accusations made about the cult leader, and in one case that I am familiar with, the abductee's fiancée was accused of cheating on him! The methods used by deprogrammers appear closer to what would be consider brainwashing than what the cults actually engaged in.
If cults, in particular the one I was involved in, had brainwashed their members, it would stand to reason that it would be difficult for someone to leave. Yet during my own involvement I saw people freely walk away, new people, as well as those who had been in for decades. My own cousin, who got me involved, walked away within a year, presumably because she decided that it wasn't providing anything that she wanted or needed that she wasn't getting anywhere else.
Finally, in the United States we have the right of free association, as well as the right to the religion of our choice. No one has the right to forcibly convert (or de-convert) someone else...even if they think the other's beliefs are harmful...or weird.