[stepbeek]

Any stateless service can be scaled horizontally. But the fixed cost of running the JVM is higher than the runtimes in other ecosystems (say a rust application as an extreme example). The JVM has had an outrageous amount of effort put into having it scale well for large heaps with high CPU counts.

As the OP points out, GC in java-land isn't worth writing home about on 1vCPU. When you throw a 16GiB heap at it though, with 16vCPUs then you'll unlock some of the really interesting optimizations and garbage collectors that the showcase the JVM in an advantageous light.

So it's not that the JVM can't scale horizontally - that's a matter of system architecture - it's that scaling it as 100 tiny nodes is far less impactful than having 5 large nodes.