Monolithic applications have a lot of advantages over microservices ones. For example:

• Strong reference check accross the whole system.
• Tooling and compiler support for system wide refactoring
• Easy debugging
• Easy to trace through call chains to understand system behavior

What might be bad

• difficult to enforce architecture discipline(e.g. horizontal partitioning). Withing a monolithic application, horizontal partitioning needs human discipline, it would be a lot easier if reference between partitions are technically not possible.
• difficult to adopt different technology stack
• difficult to adopt different architecture design in different part of system.
• difficult to scale