Multirepo at scale also needs resources, there's an enormous amount of work required for version bumping and synchronizing everything. People always completely ignore all those chores. Generally, you have either a massive amount of tech debt or you have one person doing nothing but running around doing all that work for everyone else (works great if all that work seems to magically appear for you). You can also be furiously working at automating all those chores, but that's the same level of effort you'd have to throw at scaling out a monorepo--just different.

That was my point - there are issues with both at scale. Trying to pretend that one is better for everyone is wrong. You just choose your tradeoffs.