What microservices offers is loosely coupled services with very limited responsibilities and can be replaced easily and without any impact on a running service.

We only get this if we do microservices correctly. That's more or less the whole point of my comment. In many cases, teams rush into splitting their monolith into smaller chunks and call it a day. Without proper monitoring, orchestration/choreography, service boundaries, tooling, etc. microservices will drag a team into territories where they will lose control.

Unless you somehow believe that the same people writing both a monolith and microservices would opt to write spaghetti code [...]

No, I don't believe that. However, I also don't believe people who write spaghetti code will start writing better code just because now they are writing smaller components. If the team has good coding hygiene, they will produce good code whether it's monolith or microservices. But you have a point. If we are talking about components that are 200LoC, it's more difficult to produce spaghetti (or easier to recover from it). I'm not sure that's the norm, though.

As a final note: I'm not saying microservices are bad, or monolith is better than microservices. I'm just trying to introduce some nuance. I have been part of a microservices transformation and I think it was successful. But we met with many challenges along the way that were not immediately obvious from the beginning. To quote one of the pioneers of microservices architecture:

Don’t think of adopting microservices as flipping a switch; think about it as turning a dial. As you turn that dial, and have more services, you’ll hopefully have more opportunity to get the good stuff out of microservices. But as you turn up that dial, you’ll hit different pain points as you go. (Sam Newman, Monolith To Microservices)