I don't believe that company size has anything to do with whether microservices work. That's the line people are sold, but companies large and small both suck at implementing microservices, and companies large and small can both implement monoliths successfully. I think it really has to come down to the individual case of a given product/project. One product may work way better as one architecture versus another, regardless of how many parts it may involve, due to the context, customers, use cases, organizational model, support model, regulations, etc.

As a general rule, we tend to use the org chart to define our architectures (Conway's Law), but many org charts are just fucked up. We should absolutely fight an architectural design that is mimicking a poor organizational model.