It's a policy of long standing on GC.

2002: "we don't really want GC to turn into a place where people go to post their complaints and criticisms of other boards." ⛓️‍💥[Removed]

2002: "GirlChat is not interested in being the site where people air their disputes about the goings on at other boards." ⛓️‍💥[Removed]

2002: "We are not interested in GC being a place for people to complain about any other boards." ⛓️‍💥[Removed]

2002: "Bitching about other boards serves no purpose here" ⛓️‍💥[Removed]

2003: "Girl Chat is not the place to air your differences with other boards." ⛓️‍💥[Removed]

2004: "You have not respected our desire not to bring out your dirty laundry on Girl Chat like we requested the last time you had an axe to grind with another forum." ⛓️‍💥[Removed]

2004: "We do not wish for Girl Chat to be a forum for airing one's dirty laundry with other boards." ⛓️‍💥[Removed]

Etc etc...