not every 'cheats' are equal, some lets you get an unfair advantage in PvP
but for most people, its because it provides some nice quality of life improvements, example:
- improved inventory management
- auto loot
- quest tracker
- enhanced HUD
I've never been a fan of "banning" users, make your server authoritative if you care about that kind of things, or better, listen to your players feedback
The process of modding a game and using cheats is the exact same: DLL injection, or MITM proxy for packets manipulation, so don't assume everyone has evil intentions only because of a open port ;)
Example of well intentioned modding community for Online games:
TrackMania: https://openplanet.dev/plugins