> I have yet to see a microservice architecture that automatically runs end to end tests before deploying.

One of the big tenets of independent services is that your APIs are contracts that don't change behaviour. As long as each individual service doesn't introduce breaking changes, the system as a whole should work as expected. If it doesn't this is indicative of either 1) a specific service lacking test coverage, or 2) doing something wrong i.e. directly reading from a microservices' database without going through an API.

Yes, I suspect some of the back and forth is the fuzziness of the term "broken build", whether that means the code literally doesn't compile or it does but the code does the wrong thing.

I agree that you can prevent merges that cause compilation errors in nearly all cases!