Indeed large numbers of small queues are an important case. But large numbers of small queues, every one of which might unexpectedly but legitimately need to grow large is not.

I don't know Erlang or Akka first hand, but I know that Go channels are inpsired by Erlang. Channels can be very numerous and are usually empty; but they are fixed size. In the rare occasion that you think a channel needs more buffering, you must say so explicilty.