Why is there no plural "kio," like "kioj?"

Question

Why is this nonstandard Esperanto?

"Kio estas en la bovlo?" versus "Kioj estas en la bovlo?" when you're pretty sure you're asking about multiple items.

This also applies if you're wondering what variety of items are in the bowl, not just one group of what are considered the same thing.

Talking about the same bowl with multiple apples in it, "Kio estas en la bovlo?" can have the following correct answers, depending on interpretation:

• "What are the contents of the bowl?"
  --> "Pomoj estas en la bovlo." (There are multiple discrete objects that are apples that make up the contents of the bowl)

• "What single thing is in the bowl?"
  --> "Fasko da pomoj estas en la bovlo." (The apples as singular set that constitutes the bowl's contents)

• "What kinds of things are in the bowl?"
  --> "La pomo estas en la bovlo." (The apple, as opposed to some other kind of thing)

Perhaps a system with plural "kioj" removes the ambiguity here, though I'm not sure! Maybe someone can explain why Esperanto doesn't have it. The other question here is: should I use it? I'm sure "kioj" would be understood, even if it doesn't appear in the Plena Ilustrita Vortaro de Esperanto.

I've found this article which explains this with "because English" and goes on to describe how English does it, but incorrectly. But that's all I've found so far on this topic.

EDIT: Now I'm also wondering about ĉiu vs ĉiuj

Dankon!

Answer 1

This is what Zamenhof says about kioj: https://web.archive.org/web/20130722062355/http://www.esperanto.org:80/Ondo/L-lr.htm (Lingvaj Respondoj, look for “kioj”)

Maybe this helps too: “Diversaj ioj”: http://www.esperanto.mv.ru/Cetero/ioj.html

Kio/tio/ktp. are supposed to refer to things and abstract concepts in a very general way, so that using its plural form would make little sense. It is neutral about number. This is modeled after natural languages (see Spanish eso [tio] and ese(s), esa(s) [tiu(j)]).

Esperanto's grammar does not prohibit the use of -j after “kio” but its meaning already encompasses the plural form, so you need to be sure you understand the underlying meaning of the word before tacking -j onto kio in every sentence.

You can construct very specific situations where kioj would make sense, but these are rare and would be most likely reworded before publication in books or magazines.

This example is given by Zamenhof himself:

Lia potenco konsistas el diversaj ioj, el kiuj ĉiu aparte per si mem estas ne grava, sed ĉiuj kune donas al li grandan forton”

His power consists of several somethings, of which each one in particular is not important, but all of them together give him great strength.

If you are going to say somethings, why not say things in the first place?