Discourse is a single-page application, so any request that reaches the server and incurs significant work will be counted as a page view. All requests for content, such as a list of categories, topics, or posts, count as page views, whether by a human or a web crawler.
Other tools generally use Javascript to count page views on the full page load, and omit web crawlers by default. Our counting is performed on the raw requests made and we work hard to only issue page views on the first load of a page or when you transition routes, such as moving from topics to the latest list.
This difference in what/how we track views typically results in Discourse showing 2-4x page views than other tools (including GA), even when omitting the crawler views from the Discourse report.