Erlang is great for distributed systems. But my bugbear is when people look at how distributed systems are inherently parallel, and then look at a would-be concurrent program and go, "I know, I'll make my program concurrent by making it into a distributed system".

But distributed systems are hard. If your system isn't inherently distributed, then don't rush towards a model of concurrency that emulates a distributed system. For anything on a single machine, prefer structured concurrency.