This is a personal opinion by the creator of this unofficial wiki, in which you can find hundreds of tools, scripts and studies. Since this is an unofficial site the author may mention other OTs so Deviance and other GMs can check them out.
In other OTs you will find the Global chat full of people looking to team up with strangers, and that is beautiful and a great way to make new friends and for the server to increase retention rates of players.
NoxiousOT is different, there's no real benefit of teaming up except for doing certain Quests, yet there is a huge risk due to how PVP works and how it is basically unpunished, making the risk of getting PKed not worth the effort of meeting new people. Which brings me to the next point.
This may come as no surprise, but it's always the same group of players that run the server. And there are no measures to try to balance the game whatsoever.
You can easily and quickly get abused and not be able to do much else. If you are being PKed by these groups of people there's not much you can do but put a bounty on them, which is useless since they protect each other in large groups, no one looks at bounties and other players prefer not to get PKs angry to avoid being hunted.
Killing other players gives so much experience that these PK teams can level up faster by killing other players than by normal monster hunting. As an example, a level 223 got 2,000,000 exp along with 2 more players by killing a level 290, that's around 3 hours of hunting completed in a second with UE combos.
It is also impossible to do anything about it, a handful of PKs can kill any player (regardless of his level) in seconds, and new players won't be able to defend or seek revenge whatsoever. They can't form friendships because players either avoid trusting each other or they'd rather kill them for the experience. So new players end up leaving NoxiousOT for some other OT like Medivia.
A few solutions:
Deviance (the creator and owner of the server) has abandoned the game, there's rarely any new updates (apart from usual season events) but no gameplay tweaks, and no one is dealing with rule breaking like MC-PvPing or Event AFKing.
Is it a matter of economics? Then make it slightly more pay-to-win, while it's not ideal, it may help motivate Deviance to dedicate some time to it. I'm not talking about private spawns, those where too overpowered, I'm talking about a Rebirth area for people that pay, it'll be a shared space but privileged to those who pay a subscription.
If money is not an issue, pay someone to help! GMs are always complaining that it is hard to find staff, but they haven't tried hard to be honest. I understand there's a ton of 9-year-old trolls playing the game, but there's also mature adults with a great education that can help out. And pay them something, that helps keep staff motivated.
If it's a matter of trust, implement ways to verify moderator actions, such as gathering proof of any disciplinary action in case someone complains, let players easily report moderators. Also, write down how moderators should act and the specific punishment, this doesn't need to be published but just so every moderator is consistent.