Final answer:
The Skellig's popularity as a pilgrimage site is connected to the desire for a devout religious experience away from urban distractions, reflecting the historical trend of pilgrims seeking monastic sites for ascetic living and a closer connection to God.
Step-by-step explanation:
The information that the Skellig was once particularly favored as a place of pilgrimage is most plausibly connected to the passage assertion which states, "By contrast, churches and synagogues were located in often crowded cities, where attendance at services was a daily life for laypeople. But these religious centers had to compete with other concerns for people's attention." This assertion implies that the Skellig, being a monastery, would be a site for those seeking a more intense religious experience without the distractions of urban life, thus attracting pilgrims seeking solitude and direct communion with God.
Furthermore, the existence of monasteries in harsh environments where monks could live an ascetic life, as mentioned in other sections of the text, also supports the idea that Skellig, with its remote location, fits the historical pattern of sites that attracted pilgrims. The allure of such places for pilgrims, who were seeking to be closer to God, also explains the interest in Skellig as a site for pilgrimage.