I think it extends from whatever rules govern the much-more-influential word "No", particularly for items which aren't normally capped at 1. Notice how these are all plural , and in each case "no" could be substituted with "zero": * "My shelf contains no books." * "Snails have no legs." * "What if there were no stars in the sky?" You can't simply replace those examples with a singular noun: You're either forced to re…
"My shelf contains no Elf-on-a-Shelf" / "My shelf contains no elephant" / "My shelf contains no Hemingway book." / "My shelf contains no book by Hemingway."
(For an example of the third: "Don't look there for a copy of 'The Old Man and the Sea'? I detest Hemingway, and my shelf contains no Hemingway book." In this case, 'no' means something like 'not even one'.)
As for the others, "legs" rarely come in a singular form. There is (usually) only one king for an entire population, and there is (usually) only one soul per creature, so these singular forms are just fine:
"Snails have no king." / "Snails have no soul."
There's usually a lot of stars, but our solar system has but one sun, making the following singular form just fine:
"What if there were no sun in the sky?"