Must writing always be done in the tone/style of ordinary contemporary speech?
For example, some people might say that the conjunction "for" is archaic and should not be used in modern prose, but it seems to be a part of modern English according to grammar guides and the dictionary. The argument seems to be that since no one talks like that, no one should write like that.
But is it wrong to use the conjunction "for"? Do people always have to write in the tone of ordinary speech?