Question: At the bottom of the Omud the Gemora asks in regard to the opinions of Bais Shamai and Bais Hillel "do you mean to say x amount of walls are a d'oraysa?" When the Gemora asks in regard to Bais Hillel it seems surprised that he might hold 3 mechitzos are a d'oraysa and the Gemora says know 2 are.... Why didn't the Gemora say "yes, that is what Bais Hillel holds and you still need something on the 4th side as a Heker? This is according to my understanding what he really holds, why then doesn't the Gemora say it?
We find that Rebbi Yehudah and the Rabanan argue whether mid'Oraisa two Mechitzos are needed or three are needed in order to make an area a Reshus ha'Yachid (Eruvin 6b and other places). Therefore, the Gemara did not want to set up the Machlokes between Beis Shamai and Beis Hillel in such a way that it would come out that Rebbi Yehudah was saying the same thing as Beis Shamai. Rather, the Gemara prefers to set up the Machlokes so that Rebbi Yehudah and the Rabanan both hold like Beis Hillel and are arguing within their opinion.