The point is that we don't really care about the number of uniques or page views. What we actually look at internally on a day to day basis is the amount of time people spend reading and other engagement metrics.
Whether someone spent a second or a year with the page open is irrelevent to how many servers you need to have running.
How many pageviews or requests per second is.
Aince this is an article about infrastructure no body cares about Engagement time.