In discussing why the first and second generations of the Salaf poured on the subject of abrogation, Dr. M. Ibrahim Faaris, in his book صفوة الراسخ في علم المنسوخ والناسخ, page 53, says that the reason is:
ليتحرزوا من العمل بما رفع من الأحكام ويعملوا بالمحكم منها
Translation: "So that they avoid complying with lifted rulings and comply with those of them that stayed."
In other words, not because they wanted to know if some rulings have been canceled but because they assumed that some rulings have been canceled and they set out to classify them! But if rulings have been canceled, wouldn't God or His Messenger have said so unambiguously?
Of course. And God never said once that any of His rulings has been canceled. And the Prophet (PBUH) did say that some of his rulings he has canceled and said so unambiguously. For instance, he told us that he had once allowed temporary marriage, but "God and His Messenger are forbidding it till the Day of Resurrection", narrated by Sabra Al-Juhani and reported and authenticated by Muslim.
Rulings of God cannot be canceled by man. Only God, or His delegate Prophet Muhammad (PBUH) have that authority. And no guess from a mortal as to validity of God's rulings is binding on anyone.
I submit that the first generation, the Sahaaba, wrote about naskh and not about abrogation, and their reason was not to avoid complying with some rulings, but rather to understand all aspects of a ruling, which is what naskh does. It was the second generation that changed the word naskh to mean abrogation.