I’ll say up front that Steve is completely right on this one. To begin with, even the very concept of the “emphatic pronoun” is so frustratingly nebulous so as to provide no basis for determining what is and what isn’t an emphatic one.
Steve has already done an excellent job dealing with the question of whether of pronoun is or isn’t “emphatic,” showing that it is often the case that a pronoun merely provides a “frame of reference” for the speaker’s audience. So I’ll deal with a different issue: the idea that this usage of the pronoun as either providing a frame of reference or being marked for Focus/emphasis is a result of the fact that the verb carries enough information by itself to mark the Subject of the clause.
The existence of the pronoun by itself with an agreement marking verb means very little — whether in Greek or in any other language. There are languages where there is absolutely no agreement marking on the verb at all. Chinese is a good example of this.
Mandarin Chinese (as well as other related languages) do not possess any sort of subject agreement markings on its verb at all. And yet, Mandarin is also highly driven by pragmatics, so much so that once a topic is established, that element is does not need to be referred to again. When we combine this with the fact that the verbs don’t mark the subject at all, we find a situation where early non-native speakers (especially whose first language is English) can barely follow a conversation. All of the active referents in the discourse have all dropped out and they have nothing to follow.
All this to say that both Koine Greek and Mandarin Chinese have similar pragmatic systems which regularly drop pronouns from the sentences and only add them for specific pragmatic reasons. And yet, in Greek we have verbal agreement morphology and in Mandarin, we do not. This isn’t to say that the verbal morphology cannot be the cause of Greek’s pragmatics. It simply means that there is really no way of knowing the origin of pronoun drop in Greek at all. It might be the verb’s subject agreement. It might not be.
LaPolla, Randy J. Grammatical Relations in Chinese: Synchronic and Diachronic Considerations. PhD dissertation, University of California, Berkeley, 1990.
“Inflection.” Wikipedia. Cited 12/14/2009.