Honestly, a big reason for separate services is cultural. It tends to be easier to assign accountability and ownership when you are operating a service (monitor

Honestly, a big reason for separate services is cultural. It tends to be easier to assign accountability and ownership when you are operating a service (monitoring, independent deployment, KPIs fall out more naturally). With a monolith you have to work really hard to prevent a diffusion of responsibility. Yes, to some extent this means you are "shipping your org chart", but that's mostly inevitable at scale anyway.