The principle is very consistent: You can't do something that gives you an unfair advantage over other competitors. Everything banned basically falls into one of three categories:
- It would be prohibitively expensive for others to adopt the technology. This is why you have weight minimums for bikes, boats, etc.
- Others would have to risk their health to compete. This is why you have bans of performance enhancing drugs, blood doping, etc.
- Others would have to break the law to compete. This is why you have bans on illegal drugs, even if they're not necessarily performance enhancing.
Occasionally things are also banned to preserve comparability to current records or to preserve the aesthetic sense of the sport, but for the most part when something is banned it's for one of the three enumerated reasons.