Both have boxes of stuff and the stuff talks to other stuff.
Logistically its a bit easier to scale the one where the boxes are married to closer to the hardware abstraction (microservices on instances) versus the one where boxes are married to the software abstraction (threads with memory), for the same reason one (monolith) is a lot faster (dev/process/latency) (at small scales) than the other (microservice).
You can scale both, really its mostly about fights about the tooling, process, and where your sec-ops decided to screw you over the most (did they lock down your environments or did they make it impossible to debug ports/get logs).
Practically, AWS is expensive, and they're bloated. Cluster environments that let you merge 1000 computers into 1 big supercomputer and have 1 million cores/terabytes of ram, come with different technical challenges that not as many people know how to overcome, or expensive hardware bills.
So I'd say if someone tells you it "has to be" one or the other they are blowing smoke. Micro-services were recently the hip-new-thing so it makes sense some really really bad nonsense has been written in them so people are rediscovering monoliths (and realizing the microservice people were snake-oil salesmen). In 10 years we'll realize again that some monoliths are really badly written and some people without a clue will re-write them as microservices...
Both have boxes of stuff and the stuff talks to other stuff.
Logistically its a bit easier to scale the one where the boxes are married to closer to the hardware abstraction (microservices on instances) versus the one where boxes are married to the software abstraction (threads with memory), for the same reason one (monolith) is a lot faster (dev/process/latency) (at small scales) than the other (microservice).
You can scale both, really its mostly about fights about the tooling, process, and where your sec-ops decided to screw you over the most (did they lock down your environments or did they make it impossible to debug ports/get logs).
Practically, AWS is expensive, and they're bloated. Cluster environments that let you merge 1000 computers into 1 big supercomputer and have 1 million cores/terabytes of ram, come with different technical challenges that not as many people know how to overcome, or expensive hardware bills.
So I'd say if someone tells you it "has to be" one or the other they are blowing smoke. Micro-services were recently the hip-new-thing so it makes sense some really really bad nonsense has been written in them so people are rediscovering monoliths (and realizing the microservice people were snake-oil salesmen). In 10 years we'll realize again that some monoliths are really badly written and some people without a clue will re-write them as microservices...