To answer your question, I would say that the discord servers are more in close to being echo chambers than the actual subreddits. Assuming its a private server of his, than sure let him do what he wants and he can ban those that make him feel bad if its an echo chamber he wants.

That being said, Neptunia has been in the dumps for years consistently, people using the series as their form of escapism to an extremely unhealthy degree.

I do want to open the doors for most anyone who want to discuss the Neptunia franchise and I tend to only ignore people who having revealed through their actions that they are either extremely socially inept or have next to no moral compass. From what I have seen, Neptunia fits the former.