This did not mention the front end at all. In my opinion getting a front end anywhere near as slick and powerful as Mixpanel's is an even bigger challenge than

This did not mention the front end at all. In my opinion getting a front end anywhere near as slick and powerful as Mixpanel's is an even bigger challenge than the data pipeline. The Google Reference Architecture diagram shows spreadsheets, which would require a bunch of handroll queries, and BI tools like Tableau which would be another cost and another big custom query integration job. I've seen PMs spend hours in mixpanel quickly generating custom report after custom report to really understand their data, none of these other front ends would come close to that flexibility for non-technical users.