The way bans on reddit have tended to work is that by dispersing the group, there's an additional barrier created to stop the spread of the idea. This has happened with fatpeoplehate, the trump reddit, and with the red pill reddit among others. Its not just a group of people of a similar knowledge level and similar ideas coming together, it is also new users happening across the subreddit and deciding to take part. Take away the new users and it becomes an echo chamber.
This is what makes Youtube, Reddit and Facebook so powerful. They can choose who can stay on their platform, and how much discoverability their ideas have if they are allowed to stay on the platform.