It has to do with the political migration happening during the century leading up to Book 1 of the Lone Wolf series. The Brotherhood, long active in Sommerlund court intrigue, has been steadily trying to limit its connections to the ruling line in an effort to both focus their efforts on the arcane and reduce the backlash that might occur to it should something tumultuous occur to the crown.
It's also a factor of the infiltration of Darklands agents trying to destroy the Brotherhood from within. They have been whispering thoughts of isiolationism into the ears of the leaders of the various Brotherhood guildhouses, especially in Toran. While they have not been entirely successful, the Brotherhood of the game's timeline is not as active or reactive as it used to be (or becomes again during the gamebooks).
I hope this helps!