The Importance of [Talmudic/Rabbinic] Citation

There is a famous statement found in the "sixth chapter" of Avos (even though this chapter isn't actually mishnaic, nor even tannaitic, per se):

כל האומר דבר בשם אומרו מביא גאולה לעולם, שנאמר ותאמר אסתר למלך בשם מרדכי

Anybody who says a statement in the name of the person who said it brings redemption, as it is said (Esther 2.22), "And Esther spoke to the king in the name of Mordekhai."

Ironically enough, it is introduced with the phrase "You have learned" without identifying who spoke it. This brings us to the first question: Who said it?

-In Sifre Bamidbar (section 157, s.v. Vayomer Elazar), it is Rabbi Yoshia, a tanna, the earliest dating of this statement.
-Similarly to what appears in Avos, it is mentioned twice unattached to anybody (again, ironically) in the Babylonian Talmud (Hullin 104b & Niddah 19b).
-The third time it is mentioned in the Babylonian Talmud, Rabbi Elazar says that Rabbi Hanina said it (Megillah 15a).
-Lastly, in Midrash Tanhuma (Bamidbar, section 27 in the Buber edition, section 22 in the Warsaw edition, s.v. Vaydaber hashem), Rabbi Hezekiah and Rabbi Yirmiyah, son of Abba, said that Rabbi Yohanan said it.

The latter two sources indicate that it originated in the second generation of amoraim, and poignantly being brought by others citing the particular sages.
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Now moving onto the content of the statement. I don't think it's due to the problem of [intellectual] plagiarism that it was generated. Did whomever say it really believe that it would bring redemption, or was it just a nice thing to say? Or was it said due to a hermeneutical read on the Esther verse? What's further interesting to ask is how important was it the sages to quote others? Was it just a nice thing to hopefully bring redemption or was it a mandate in order to do so? Did they always or were there sometimes that they didn't say something in the name of the person who originated it?
I would imagine that the amoraim were particularly מקפיד (careful) about this, though the tannaim might not have been so(?). Obviously, the stammaim were not as concerned about it - why?
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So, one might ask, "What's the significance of this point?" (or in Aramaic למאי נפקא מינה). Simply put, the answer is intellectual history: both for the development of ideas and halakhah, as well as for understanding more about our sages (unless you're a Neusnerian).
I first became interested in understanding the sage behind the statements in the spring of 2004, when I was studying in yeshivah in Israel (yes, I know Ohr Somayach is a strange place to be concerned about our sages, per se, rather than just the ideas) and I have become more interested since then, especially last year in yeshiva.
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Tags: Talmud, Judaism, Sages, Jewish sages, intellectual history, Jewish intellectual history, citation