It is not a binary flip between monolith and modular monolith, it is on a gradual scale, and I saw teams moving toward modularity with a various degree of succe

It is not a binary flip between monolith and modular monolith, it is on a gradual scale, and I saw teams moving toward modularity with a various degree of success. They may not even use the term of distributed monolith to name their approach. Sometimes, they do it to keep the monolith maintainable, sometimes as the first steps towards microservices - defining boundaries, simplifying dependencies certainly help against the antipattern of distributed monolith. Ideally, the decision to build modular monolith should be made and implemented from the very start of the project. Some frameworks like Django help with keeping separation. I found that fitness functions help with policies and contracts. You run then in your CI/CD and they raise alarm when they detect contract / access violation across the boundaries.