"Whom" is also almost impossibly archaic and no longer considered part of modern English (having almost completely fallen out of usage around the start of the 20th century). It survives almost entirely in discussions of when to use it and almost never appears in modern writing except as a demonstration of what linguists call a "prestige form".
"To whom did you give it?" vs. "Who did you give it to?" the latter is more modern and natural in modern English.
Huh. Really? I use whom all the time, and most of my friends do as well. Granted, a) we're all snobs, and b) we don't use it in every case we should, but we still use it.
"Whom" makes you sound a bit dated. Etymologists will get the joke. ;-)
(I suppose I should explain it. "Whom" comes from a dative case, and would is not descended from a word that would be used for direct objects, but only for a subset of indirect objects and prepositional objects. However if elative uses relate to elated things, then surely dative uses in English relate to dated things, right?)
So ask yourself the question, why not "thee", "thou" and "thy" (and relevant possessive forms)? I'm not saying "whom" is wrong only that it is archaic. Reviving just that word seems rather capricious and arbitrary no?
I would say "whom" today is reserved for formulaic usage.
In 1912, Edward Sapir ("Language: An Introduction to the Study of Speech") noted the death of "whom." The example he gave was "Whom did you see yesterday" vs "Who did you see yesterday?"
Granted there are some cool things you can do with who/whom, like:
'Scots, wha hae wi Wallace bled,
Scots, wham Bruce has aften led,
Welcome tae yer gory bed,
Or tae victorie.'
Of course that's 18th century Scottish and things have changed a bit....
"To whom did you give it?" vs. "Who did you give it to?" the latter is more modern and natural in modern English.