Q: What is “朝聖" in English?
A: The direct translation would be “to make a pilgrimage (n.) 朝聖.”
A more colloquial translation for the usage you see on ptt would be “to gather around to see a show.”
That is, when people “朝聖” on ptt, they are basically gathering to see an event unfold (展開).
Since they feel that they must do this, much like how a pilgrim has to make a pilgrimage, they use the term ”朝聖.”
A related term would be “to leap on the bandwagon,” a phrase that means to support something popular.
jump/leap on the bandwagon
1. While everyone on ptt is busy “making a pilgrimage” to a specific post and adding needless comments, the world is quickly moving by. Once again, a day of progress is lost.
2. Posters on ptt often leap on the bandwagon and enforce mob justice (暴民的正義) with little regard for due process (正當程序).