> "why can't just just put your millions of events into a service bus and write some backend to react to them to update your aggregate". Yes we CAN do that but why do that it's 15 lines of SQL and 5 seconds compute

Do people actually do this? I feel like this is classic Occam's Razor. This is one of the biggest things I do in SQL and I couldn't imagine the time and effort to do it with a separate service.