I think it's maybe an argument for a single repo per (two-pizza) team. Beyond that, you really don't want your components to be that tightly coupled together (e.g. you need each team to be able to control their own release cycles independently of each other). Conway's law works both ways.
If they have independent release cycles, they shouldn't be tightly coupled (sharing models etc. beyond a specific, narrowly-scoped, and carefully versioned API layer), and in that case there is little benefit and nontrivial cost to having them be in a monorepo.
