Running highly scalable monoliths is easy! As long as you’re willing to hire some of the five to ten people in the world who are capable of advancing the state of the art of development on that technology stack…

I truly believe that being able to design and run a modular monolith application effectively (not talking about the 'hyperscale' scenario here) should be a prerequisite for designing and running a set of interconnected microsservices. The challenge is similar, but dealing with modular monoliths has the advantage of not having to deal with the uncertainty of networking programming (i.e. remote calls, network error handling, distributed transactions).