The other day I've made a Chrome extension for scrapping a protected website. It worked wonderfully, as it simulated a normal user session, bypassing the JavaScript protections the website has. You can also run such scripts with a headless browser for full automation, PhantomJS being an obvious choice.
You really can't protect against this unless you start making the experience of regular visitors much worse.
You really can't protect against this unless you start making the experience of regular visitors much worse.