@lackthereof @pgcd @leymoo @codinghorror Maybe we're going by different definitions of "session". It sounds like you think it's a short-lived thing that disappears when you terminate the browser. Which, even if that were the definition, would still mean it... never disappears. Most of us have browser "sessions" 10+ years old. Mobile doesn't even have a sense of terminating the browser.
The definition I'm going by is an identifier, regardless of lifetime, that establishes distinct HTTP requests as originating from the same browser. There is no "strictly necessary" reason to do this unless the purpose of the site is maintaining a stateful interaction with the user. If the visitor is just reading your site, there is no legitimate business interest in knowing whether the load of page A and the load of page B came from the same person.