Ugh. Yeah, this misses the point: not everyone wants their content archived. Of course, there are no feasible technical means to prevent this from happening, so

Ugh. Yeah, this misses the point: not everyone wants their content archived. Of course, there are no feasible technical means to prevent this from happening, so robots.txt is a friendly way of saying "hey, don't save this stuff." Just because theres no technical reason you can't archive doesn't mean that you shouldn't respect someone's wishes. It's a bit like going to a clothing optional beach with a big camera and taking a bunch of photos. Is what you're doing legal? In most countries, yes. Are you an asshole for doing it? Also yes.