there are only so many hours [for Linus] in the day. It
is, as a practical matter, necessary to communicate that
there is a cost to wasting his time with work that
somebody should have known was substandard
This is a really a restatement of the old (yet still relevant) "Linus doesn't scale" issue, right?
It's true: Linus' time is a valuable resource and shouldn't be wasted. This is of course true of any project maintainer, or any person at all really -- it's just that the stakes are a higher in the case of the Linux kernel because of the scope and impact of the project.
it is important that that cost is borne primarily by the
originator of that substandard work (i.e. it needs to suck
more for the committer to waste Linus' time than it sucks
for Linus to spend time responding)
This is a nearly universal problem.
Imagine suggesting "hurl insults at the perpetrators until they learn" as a solution in any other field. Ridiculous!
The answer of course is to proactively reduce the number of time-wasting things that are raised to Linus' attention, not to reactively be meaner when those sorts of things do happen.
Typically you'd do this in Linux or any software project by:
(a) making sure that the other kernel maintainers are trusted and skilled
(b) making sure that everybody has a solid understanding of what is and isn't a good contribution
(c) discussing contributions ahead of time so that there are fewer surprises at review/merge time
(d) solve the "Linus doesn't scale" issue by delegating more of his responsibility elsewhere, cloning him, etc.
I should note that I have no idea about how the kernel maintainers function on a daily basis. Maybe they're already doing a really great job of those things, and it's only 0.001% of merge requests that result in spectacular Linus rants and therefore show up on HN or whatever. Since it seems like kernel development is humming along pretty well for the mooooooost part I'd put my money on that, but who knows.