I think your examples actually proves my point: even though there are wildly different views on where the line should be drawn, we don't consider that to be a r

I think your examples actually proves my point: even though there are wildly different views on where the line should be drawn, we don't consider that to be a reason not to draw any lines. So there's disagreement over the damage inflicted on a car by various actions: the car aficionado will consider it an assault on himself if you look at his car the wrong way, whereas the hippie will shrug his shoulders and bemoan the spelling mistake if someone tagged his VW Camper van with "I sukk". But even though these differences exist, nobody is arguing that setting someone's car on fire should be a criminal offence. To get back to doping: you can reasonably argue that caffeine in huge doses is doping, and you can reasonably argue the opposite. But that's no reason not to limit EPO or genetic doping.