IP addresses are great for identifying traffic patterns, figuring out where your audience is roughly located etc. as long as you don't use them to selectively b

IP addresses are great for identifying traffic patterns, figuring out where your audience is roughly located etc. as long as you don't use them to selectively block users – since then nobody has a real incentive to "cloak" theirs. Once you start doing that, you've completely destroyed the measurement, and at the same time you're still not keeping out unintended users – because these will just use a VPN. To go with an analogy: Imagine a bank enforcing embargo/sanction policies by just asking everyone at the entrance for their name but not checking their ID! You'd get a lot of personal data (since most people won't lie), yet you won't keep any sanction evaders out.