[shroompasta]

Their architecture didn't provide any clear boundaries to be sufficient for microservices, however that isn't the case for many medium to larger sized projects.

(By the way, just because there's still quite a bit of coupling between services, doesn't mean there aren't clear boundaries - Microservices can communicate with one another all the time and still be justified in being decoupled)

There isn't an absolute answer to monolith vs microservices - It depends case by case.

Instagram was built using Django and I'm unsure of ig's architecture today, but it remained monolithic for a very long time (at least till late 2019), and if that architecture sufficed for Instagram, I'm sure it would suffice for many other projects.

However, still, it's not a this or that as many of the comments here would seemingly imply - Again, it's HEAVILY dependent on the case.