> Parallel Universe's Quasar is basically OTP for Java, so I know logically that Java is basically a superset of Erlang at this point

It's not really a superset. The JVM has a single global heap, whereas BEAM has per-process heaps. Global state is the enemy of concurrency, and the best GC algorithm is one you don't need to run at all. The "several hundred millisecond HTTP response latency and horde (sic) memory" problems you note are in part a result of having a global heap.