From what I understand, this is coming from a new EU directive which requires all EU website owners to get a user’s consent before cookies are saved onto a device.
TechCrunch Europe has an article saying the UK’s Information Commissioner’s own website has seen a 90% nose-dive in traffic
since they implemented this policy on their site! Here's the link: Want a 90% drop in your site visitors? Yes folks, you too can implement EU cookie law!
Of course this 90% drop, in reality, is in TRACKED visitors, not total visitors. But the two are not that far apart: if you cannot measure it, it's as good as not having it at all (especially if a large portion of your revenue is from advertising).