In my experience monoliths don't reduce complexity, they just shift it. The main issue with monoliths is that they don't have clear and explicit separation of concern between domain concerns, therefore it's very easy for your monolith codebase to devolve into a mess of highly interconnected spaghetti code with time. This is especially true if you're building something large with a lot of developers who don't necessarily understand all of the domain complexity of the code they're touching.
Monoliths imo are better for smaller projects with a few devs, but otherwise within a few years most of the time you'll regret building a monolith.
I also disagree with the duplicated code point. I don't understand why that would be a significant problem assuming you're using the same language and sharing packages between projects. This isn't a problem I've ever had while working on microservices anyway. I'd also debate whether they're anymore more complex than monoliths on average. My favourite thing about microservice architecture is how simple individual microservices are to understand and contribute to. The architecture and provisioning of microservices can be more complicated, but from the perspective of a developer working on a microservice it should be much simpler to work on compared to a monolith.
Monoliths imo are better for smaller projects with a few devs, but otherwise within a few years most of the time you'll regret building a monolith.
I also disagree with the duplicated code point. I don't understand why that would be a significant problem assuming you're using the same language and sharing packages between projects. This isn't a problem I've ever had while working on microservices anyway. I'd also debate whether they're anymore more complex than monoliths on average. My favourite thing about microservice architecture is how simple individual microservices are to understand and contribute to. The architecture and provisioning of microservices can be more complicated, but from the perspective of a developer working on a microservice it should be much simpler to work on compared to a monolith.