It's not even that femslash fans didn't want the canon. I remember seeing f/f BSC requests in previous Yuletides.
Also, the current breakdown of top BSC categories on AO3 is Gen (332), F/M (229), F/F (175), M/M (76). It's just that for whatever reason m/m fans in this fandom mostly coalesced around a single ship, while f/m and f/f fans shipped a variety of ships.
Re: Canon Recs - Canon Gay TV Shows
Also, the current breakdown of top BSC categories on AO3 is Gen (332), F/M (229), F/F (175), M/M (76). It's just that for whatever reason m/m fans in this fandom mostly coalesced around a single ship, while f/m and f/f fans shipped a variety of ships.