Map blacklisting was a thing for a while. For a time, you could blacklist 2 BGs.
Everything was fine and dandy, until Blizzard realized the entire playerbase was blacklisting both Strand of the Ancients and Isle of Conquest. Blizzard was very unhappy about this, and they felt personally wronged by it - insulted even. As such, they removed this feature entirely out of spite.
Correct me if im wrong, but i dont believe this feature ever returned. I think the playerbase struck a bit of a nerve with Blizzard on this one. Imagine being the dev who designed Strand and Isle? Ooof.