Yesterday morning those of us who live in the 5T had the special opportunity to hear a shiur from R’ Ahron Kahn (Rosh Yeshiva at YU) given at Mesivta Rambam. I can't capture the whole shiur in a blog post, but there was one parenthetical comment that the Rosh Yeshiva made which stands as a fascinating point in its own right. R’ Kahn noted that while Rashi sometimes is verbose in his explanation of what seems to us a simple sugya, but Rashi is often silent and offers no comment on complex sugyos that other Rishonim struggle to interpret and which challenge our understanding. Similarly, even in his commentary on chumash we find Rashi often offers no comment on texts that seem to us to cry out for explanation. The key to understanding these lacunae is to appreciate that Rashi's role was not just that of a mefareish, a commentator guiding us through difficult passages of text, but that of a ba’al mesorah, one whose task was to accurately preserve the tradition of textual interpretation that he had been taught and which he viewed as authoritative. Where the mesorah offered a clear guide, Rashi presents a succinct encapsulation of that tradition. However, where the mesorah was unclear, where there existed multiple approaches within tradition to a text and there was not a single dominant approach Rashi felt was authoritative, Rashi is either silent, or rarely, Rashi will quote multiple explanations.
(Any mistakes is understanding this point or properly conveying it are mine alone.)