TOEFL integrated writing Chaco housing

The reading and the lecture are both about what the massive stone buildings in Chaco Canyon (New Mexico, USA) were used for. Whereas the author of the reading states three possible theories, the lecturer casts doubt on the main points made in the reading by providing three reasons.
First of all, according to the reading, the Chaco structures were used for residential purposes, where hundreds of people could live there. However, the lecturer disputes this point. He agrees that from outside they looked residential, but from inside he doubts that many people could have lived there. To support this opinion, he states that inside the buildings were found few fire places to cook and there were not enough rooms.
Secondly, the reading states that the structures were used to store food supplies, such as grain maize, which was one of the principal crops of the Chaco people. Nevertheless, the lecturer refutes this argument. He claims that no maize was spilled on the floor and no containers were found.
Finally, the author claims that the houses were used as ceremonial centers, based on what was found near a house called Pueblo Alto. The author explains that archeologists found deposits containing many broken pots, probably used for ceremonies. On the other hand, the lecturer points out that more things were found near Pueblo Alto apart from broken pots, such as sand, stone or cement which were trash of construction. As a result, he suggests that the pots were common construction garbage, too.
In conclusion, although the reading and the lecture discuss about which could have been the possible uses of the Chaco structures, the three main points made in the reading are effectively challenged by the lecturer.