I can sum this up with less than a book to read.
If you always 3 man , continue. Why worry about what others are doing
English
-
Because others can affect how the game feels and how the community interacts with the game. That is why people play the meta in PvP. That is why people play specific strats in Raids. That is why people ask Youtubers primarly about their guidance instead of thinking on their own. It is a pattern that does affect the game interaction in many ways from many sides.