Well, commencing the above sentence by means of the
It-clause rather than the (here "fused" or "headless")
Wh-clause, and thereby necessarily extraposing the
Wh-clause to the end, means that the
Wh-clause cannot but be "subservient to"*, have to simply "follow on from" the
It-clause, with the unavoidable consequence that the 'free choice' ("any whatsoever") meaning inherent in
It doesn't matter would make
redundant (re. what Salner said! Welcome to the forums by the way!), i.e. pretty much make "unacceptable" and thus "prevent", any such free-choice expression (in the form of a compound-forming -
ever) appearing in the
Wh-clause; that is, here the meaning that "the actual value of
x doesn't matter"
HAS ALREADY BEEN EXPRESSED**, and outside of the
Wh-clause. All of which explains why
It doesn't matter who posts the letters seems preferable to ?/*
It doesn't matter whoever posts the letters.
If however the above sentence's
Wh-clause isn't extraposed (=replaced in the process of extraposition) by the dummy
It and its clause, i.e. the
Wh-clause has a more direct relationship with the predicate (=what Ouyang wrote!) without any
(I)t coming first and thus "intervening", then the
Wh-clause
has to contain an -
ever compound and thereby express the free-choice meaning
within itself, given that there is now no item expressing such a meaning outside of and certainly not before/prior to the
Wh-clause. All of which explains why
Whoever posts the letters(?, it) doesn't matter is acceptable and ?/*
Who posts the letters(?, it) doesn't matter "unacceptable" (or at the very least a somewhat archaic-sounding form probably found mainly, that is "only", in lines such as
Who steals my purse steals trash (from Shakespeare's
Othello)). Note however that the unacceptable sentence would become acceptable (and the acceptable one become unacceptable!) if the clauses were reversed, the bracketed 'it' (supplied by me to simply help remind one of the "boundaries" between the clauses) then brought into play, and the comma omitted...which brings us back to the very beginning of this post!
Then, the prototypical function of words like 'who' is to ask actual questions, whilst the function of 'whoever' is usually to indicate "any whatsoever is fine" (meaning, there isn't too much doubt let alone an actual "question" [exclamatory or otherwise] attached to most instances of the latter type of form; but when there
is, note that the
wh- and -
ever may then often by somewhat prescriptive convention be separated in writing by the use of a space between them).
Overall the above sentence as begun by the
It-clause would seem the more natural phrasing to my ear than beginning with a
Wh-.
*At-all technical terms like 'subordinate' and even 'dependent' won't really work here!
**Those who are familiar with some of my older posts will know that I have a bit of a thing for (the idea at least of) 'linear', more bottom-up 'incremental' grammars than top-down, 'parsed after the fact' ones: that is, "Saying A then B i.e. putting A before B, is not ever quite the same thing as saying B then A (or rather, and certainly in this thread's specific context, uttering a
possible variant of B ahead of and prior to a
possible variant of A)!".
