Google Analytics gives webmasters traffic statistics. I think one problem is, when they are selling advertising, people want the stats to come from a trustworthy 3rd party like Google. If they are relying on local metrics, it's trivial to cook the books.
You have a strong point about this being a bad match for a site like bitpay and other btc related sites.
Ty, to the best of my knowledge, I don't get any googleanalytics domain up when paying with BitPay, but they seem to rely on some google scripts from the sites mentioned in my first post.
I know google analytics is a powerful tool, but services that care about users privacy, I don't think should use google analytics.