there was a recent move from the eu to have an eu-centric public resolver which brought up the question if/how the big players address country specific filtering requirements which in turn might have shed some light on the fact that gog/cf didn't care; until now.
Oh and - given the right adlists - may also prevent infecting your machine/network/... with malware...
Not to speak of clients which may not equipped with on-device adblockers, such as TVs etc...