Software Architect's Handbook

Drawbacks of a monolithic architecture

Although a monolithic architecture may work for some applications, as applications grow in size and complexity, there are serious drawbacks. Monolithic applications greatly inhibit the agility of the organization as it becomes difficult to make changes to the software. One aspect of this is the fact that continuous deployment is difficult to achieve. Even if a change is made to only one component of a monolithic application, the entire software system will need to be deployed. Organizations are required to devote more resources, such as time and testers, to deploy a new version of a monolithic application.

If the application is small, it can be easy to maintain due to the simplicity of the architecture. ...