Why to people claim ancient archaeology was somehow flawed?

The Empress Helena (c. AD 250 – c. AD 330), mother of Constantine, the first Christian Emperor of Rome, travelled to the Holy Land, dated by modern historians in 326-28, founding churches and establishing relief agencies for the poor. It was afterwards claimed, in the later fourth-century history by Gelasius of Caesarea followed by Rufinus' additions to Eusebius' Ecclesiastical History, that she discovered the hiding place of three crosses, believed to be used at the crucifixion of Jesus and the two thieves — St. Dismas and Gestas — who were executed with him, and that through a miracle it was revealed which of the three was the True Cross.