The archive absolutely changes. Sometimes intentionally, sometimes unintentionally.
My wife is a historian. "Oh, those records were destroyed in 1920 when a new archivist took over and changed the recordkeeping methods" and "oh, the boxes with the stuff between years X and Y were destroyed by bombs in WW2" are common occurrences. Historians understand this and develop methods for dealing with this but we should also understand that the archive is never going to be immutable.
This is not to say that deliberately editing the archive is good, only that it is inevitable for reasons much more banal than what is described in TFA.
My wife is a historian. "Oh, those records were destroyed in 1920 when a new archivist took over and changed the recordkeeping methods" and "oh, the boxes with the stuff between years X and Y were destroyed by bombs in WW2" are common occurrences. Historians understand this and develop methods for dealing with this but we should also understand that the archive is never going to be immutable.
This is not to say that deliberately editing the archive is good, only that it is inevitable for reasons much more banal than what is described in TFA.