Agreed! But you're glossing over the Zanzibar point of view on this topic, which falls back to dual-writes. That approach has a lot of downsides: "Unfortunately, when making writes to multiple systems, there are no easy answers."[0]

Having spoken with the actual creators of Zanzibar, they lament the massive challenge this design presents and the heroics they undertook over 7+ years at Google to overcome them.

By contrast, we're seeing lots of the best tech companies opt for approaches that let them leave the data in their source database wherever and as much as possible [1]

[0] https://authzed.com/blog/the-dual-write-problem

[1] https://www.osohq.com/post/local-authorization

I'm founder of Oso btw.