alt Hacker NewsI don't have a statistic here, but I'm always surprised how many websites I come across that do limited user-agent and origin/referrer checks, but don't maintain any kind of active IP based tracking. If you're trying to build a site-specific scraper and are getting blocked, mimicking headers is an easy and often sufficient step.
If you can't tell the difference between active tracking and inspecting request headers, then it's worth committing a bit of time to ponder. Particularly the costs associated with IP tracking at scale.