I've often wondered why many a time the Gemara quotes statements of one Rav in the name of another. I suppose that the most probable answer is that the Oral Law was obviously handed down orally, and hence the statements were recorded in the names of those last few links.
However, what may be more accurate is that Chazal were trying to honor this saying by R' Elazar in the name of R' Chanina:
ואמר ר"א אמר רבי חנינא כל האומר דבר בשם אומרו מביא גאולה לעולם שנאמר ותאמר אסתר למלך בשם מרדכי (Megillah 15A)
What I find ironic is that more often than not, this Chazal is stated without naming Rav Elazar or Rav Chanina. What is most ironic, is that this saying is stated originally in the Mishna (Avos 6:6) anonymously!
UPDATED 4/13/2010 3:20 PM
I have given this some more thought and I believe I have arrived at the answer. Please let me know if the logic is solid.
It seems that what the underlying theme of this statement is that one should not take false credit for himself. It is a form of stealing. Esther could have used the information that Mordechai provided her for her own self promotion, yet she rightly refused to take the credit.
Rav Elazar in the name of Rav Chanina is teaching the message that it is a Geneivas Daas to have someone else think more highly of you than is rightfully so. Therefore there is no need to mention them when repeating this dictum. Everyone knows it nowadays. But not everyone knew about Bigsan and Theresh’s plot. That would have been incorrect for Esther to make believe that she became privy to that information on her own.
The idea is not to go around repeating that I heard this from so and so. The idea is that one should not go around taking credit for someone else’s intellectual property/chiddush.
When you repeat this chiddush to someone, tell them you saw it on SoMeHoW Frum!