105 points
Only a very tiny number of Linux users spoof their browser’s user agent, which these statistics are based on.
70 points
The issue is whether the data is collected by a known third party tracker domain which would be blocked by an adblocker
17 points
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Large sites usually have their own first-party analytics. Often they don’t want third parties to be in possession of detailed analytics data.
21 points
Pornhub mentions that they use Google Analytics about halfway down the page in the section “Proportion of Female Visitors”