If too many are
accumulating, it's probably due to a programming error that needs to
be found and fixed by human inspection. (Tim just made several
commits fixing things that were spewing out too many jobs.)
(Obviously, the length
of the job queue needs to be added to whatever diagnostic screen the
devs first check when the site slows down, otherwise it won't help
much.)
#wikimedia-tech has enough people that regular warnings posted there
would probably get noticed.
People did complain about long job queue on #wikimedia-tech. I don't
think they were taken too seriously.