«وَأَمَّا الْإِجْمَاعُ فَلَيْسَ بِنَاسِخٍ، بَلْ يَدُلُّ عَلَى ذَلِكَ»
Consensus does not itself abrogate; it can point to an abrogation.
The distinction is between the later legal proof that abrogates and an indication by which the existence of that change is recognized. Where a sound consensus establishes that an earlier rule no longer applies, the investigator seeks the underlying proof or explanatory basis rather than treating consensus as a new revelation directly replacing the earlier ruling.
Not every widespread legal practice or summary of scholarly opinions establishes a rigorously demonstrated consensus.