Manpage for send says:

ENOBUFS
              The output queue for a network interface was full.  This generally indicates that  the  interface  has  stopped
              sending, but may be caused by transient congestion.  (Normally, this does not occur in Linux.  Packets are just
              silently dropped when a device queue overflows.)


So ENOBUFS seems to be designed to have the role that you envision. We
just need to remove the statement in (). Its still a change in behavior
though.