“These are the words that Moshe spoke to all of Israel, on the other side of the Jordan, concerning the Wilderness, concerning the Aravah, opposite the Sea of Reeds, between Paran and Tofel, and Lavan, Chatzeiros, and Di Zahav. ” 1:1
These are the words - Because these are words of rebuke, and because Moshe intended to recount here all the places where they angered the Almighty, he therefore said these words in an obscure manner and only intimated that they sinned in these places. This was done in order to uphold the honor of the Jewish people. - Rashi
In addition to serving as a model for how to offer effective rebuke, there may be another reason behind the indirect presentation. Perhaps Moshe was pointing out that some of these sins were not nearly as deliberate and overt as one may be led to believe from the Torahs’ earlier accounts of them. Sometimes a sin can be a deliberate act of defiance, and sometimes it can be as subtle as an improper thought, motive, or attitude. While the latter is certainly undesirable as well, in terms of severity, they are nevertheless, a far cry from the more blatant forms of sin.