RDBMS doesn't work but columnar databases such as BigQuery, Snowflake, and Presto make it work. I agree that web/product analytics data is hard to get it done the right way thus people rely on specialized solutions such as Mixpanel and Amplitude but I believe that as companies started to be more privacy-concerned and want to fill the gap in between the product and other company data such as marketing, finance, etc, it will change over time. See how it's possible to run funnel, retention, segmentation queries in Firebase Analytics data on BigQuery with SQL: https://www.youtube.com/watch?v=7tXVG785_0M