> Sort of; at medium scale you can blue/green your whole system out of the monorepo (even if its say 20 services) in k8s and flip the ingresses to cut over during release.

That's overall a bad idea, and negates the whole point of blue-green deployments. This is particularly bad if you have in place any form of distributed transaction.

There are very good reasons why deployment strategies such as rolling deployments and one-box deployments were developed. You need to be able to gradually roll out a change to prevent problems from escalating and causing downtime. If you use all that infrastructure to then flip global switches then you're building up all this infrastructure to the negate any of that with practices that invariably cause problems.

And this is being done just because someone thinks it's a good idea to keep all code in a single repo?