As has happened in the past, the Nephite people continue to be divided both politically and religiously. Even with this renewal of belief in the gospel, there are dissidents who prefer the Gadiantons over the gospel. They demonstrate that preference by leaving and joining with the Gadiantons. We should remember that not that many years prior the entire Nephite world was governed by Gadiantons, so there were many who had been sympathetic.
One of Mormon’s themes for the destruction of the Nephites has that destruction linked to internal apostasy. Thus when he begins a narration of the destruction impact of the Gadiantons, he makes certain to also note that they are joined by dissident Nephites. The destruction of the Nephites will always come at the hands of the Gadiantons, but the Gadiantons will always include apostate Nephites. This will always be a destruction that they bring upon themselves through their own choices and apostasy.