This isn't a quantitative opinion, but here's how I think about it. Generally hate springs from some kind of problem or ideological bent in a person's life, but those problems and bents are initially undirected and latent. Eventually, someone comes up with a story that speaks to these impulses and describes why a particular group is the cause of their ills, despite ahistoricism or any kind of grounded logical argument (some groups can be actual problems such as slave masters or a literal invading army).

The inchoate pain these latent hate group members feel could be resolved in another way by accurately portraying the source of their problem, and giving them a realistic way of solving it. However, often in our society, we don't provide these things. Therefore, they remain susceptible.

When a hater that tells a powerful narrative gets together with others, this becomes dangerous. The group now validates their beliefs and it becomes self-reinforcing and actionable.

Deplatforming prevents hate groups from getting new recruits by making these stories and groups harder to access. It also is a message to the more marginal members that what they are doing is shunned and they should think hard about what they are doing. Essentially, the idea is prevent these small scale problems from turning into a social movement that would be highly destructive.

Is it a bandaid? Yes. We have to work much harder on our social and economic problems to make sure everyone is included in society and can live a decent life. That would remove much of the impetus for joining hate groups.