I guess like you said: common courtesy, don't waste my time or yours. Why send an email if its' not worthy of a response?
The former is certainly true; the latter, probably not.
I'd simplify to: "It's a rational strategy that maximises coverage."
Being rejected is unpleasant in any context; one way to minimise the unpleasantness is to downplay the value of any one interaction.
If you make a big effort, the disappointment is magnified. This is why the first and most important advice to folk on dating sites is "message and move on". Otherwise you're going to get bitter, which is even more self-defeating.
Rejection is painful because of the "simulation heuristic" -- imagining yourself enjoying working at the place / going on dates with the person.
The simulation heuristic works the other way too. You can easily imagine being disappointed by the new restaurant. You know what? Let's just go to Shmookey's, we always go to Shmookey's on Thursday and get the steak.
edit: actually, no, simulation heuristic isn't quite right. Sunk cost fallacy? Someone help me out here.
Of course, the counter to that is that taking a dump in a thousand baskets also leads to no eggs.
While the quote is very funny and I give you that, the analogy doesn't fit. A more apt analogy would be - throwing your eggs without care in a thousand baskets, chances are most eggs will break.
How would you describe emailing a hiring manager/developer with something like "lol, give job pls?" Not very egg-like at all...