Some background information: I think you might misunderstand the very idea of Rabbis in times of the second Temple and up to the signing of the Talmud. As we know, the winner rewrites the history. That's what happened, in my understanding, with our sources - all of them were "aligned" with the winning Pharisee view, especially presenting our forefathers (up to the second Temple time) as keeping exclusively the Pharisee tradition for all times.
THis is not true, of course. Practically all of the Rabbinical rulings were a matter of public acceptance over long long time. The fact that the Mishna itself is full of mutual nonacceptance of numerous Rabbis proves it. Many even question "one vs many" rule and many time on wins over many. This is especially weird in times of the functioning Sanhedrin, where the question could be simply ruled by the Sanhedrin - but nobody used that option, proving that there was not unanimously accepted Halakhah until Rambam and Shulchan Aruch.
Another point to keep in mind - there were no written laws before the Mishnah, everyone wrote note to himself, so instituting a ruling was practically impossible.
Also, during the Second Temple the Rabbis had no social or political influence to enforce their ruling unto the masses. Jews were scattered all over a huge region with no central power. Even under R'Gamliel's political alliances it was very local. Remember R' Yahosua that did not accept R' Gamliel Beis Din ruling of Rosh Chodesh (Berachot 18)? The Talmud is full of such examples when Rabbies had conflicting customs in different towns and even neighborhoods of the same town.
To your question of Chanukkah: same here. The way the Talmud presents it as hinted in the Torah and practiced for generations is not so true. It was not widely practiced until long after the destruction of the Temple as it did not make a dent in the Mishna.
It is also true nowadays. Rabbis write their ruling as sort of "שלח לחמך על פני המים" - "spread you crumbs over the water" as they have no real enforcement power, and it takes years and sometimes decades and more to see, which rulings are accepted and which are not and by whom.