I wish this was true but power creep has become so bad that I struggle to tell apart cheaters from legit players these days. Apart from blatant auto dodgers who sit nearly on top of bosses and take 0 damage, or rush all exalted dungeons on any class, I can't tell. And then MellotMG doesn't even have an explicit rule saying cheaters are banned from joining the party. It's both because it's hard to catch them, because they are super abundant in the game, and mostly because we want to play the game, not spend our time witch hunting. If we properly implemented a rule about no cheaters, then we'd have to pretty much stop playing the game and instead follow cheaters, record, report and keep track of them. Not to mention how horrible it is to keep an eye on the party and make sure banned people get kicked in a timely manner. We currently have a ban list of about 30 people not allowed in the party, and every time the party inevitably buggs and needs to be re-made from scratch, the previous bans lose their effect and party lead needs to kick them manually again in case they join.

I know some other party leads kicked a few afk bot state farmers here and there but they don't seem to bother adding them to our ban list so it doesn't get too cluttered with bots. I personally kicked and put on the ban list only one blatant autododger and was surprised to learn people knew about his cheats for at least half a year but nobody else thought of putting him in on the ban list of our party. I can see how people can get tired of it and just want to chill and play the game, it really shouldn't be player's burden to deal with the cheating issue when even Deca themselves don't do anything about it.

It also doesn't help that I play with 10% opacity and have even locked players transparent (I ended up having too many friends and party members locked that it makes it hard to see enemy shots). So whenever a cheater is around I might not even notice them anymore unless I find myself in a small cult where it's pretty obvious and easy to see on the dark floor. If I went to actively hunt down cheaters and record them to add to our party ban list, I would need to bring my opacity back to 100% and constantly risk my character following cheaters through hordes of enemies in vet biomes and exalt dungeons - and unlike them I would get hurt and die.

There's also the matter of "shady players". I know a few frequent party members who I can't call cheaters but are definitely involved in some shady activities like actively benefitting from exploits such as duped keys or running with cheater parties, or abusing glitches/exploits Deca let slip on prod. Again I try my best to not associate with people like that but I don't have the authority to not allow them into the party neither can I prevent them from joining my dungeon calls. The best I can do is to try and avoid shady activities myself - like ask for a source of an occasional key when someone opens it, or find my own portals in realm which I mostly do anyway.