There isn't a universal 'I'm a bot' setting. There are user agent conventions, but they are hardly standard. Your point works in theory, but it's not something one can just implement and be reasonably confident that they won't be scraped.
No, it won't prevent being scraped. That's not the point I was making.
The point is, the scraper would have to hide their intentions and identity, which removes any claim they are being 'honest' in their intentions and not trying to circumvent the provider of the services efforts to prevent scraping.
