Well, yes, but there is also this person called Sam, and Wincest went almost entirely uncontested for three whole years. Apparently once you spend all that time justifying your incest pairing to the internet at large, you get a little invested in it? (On a non-shippy writerly note, lots of fangirls are also accusing the writers of privileging Castiel's character arc above Sam's, and since we can't kill the writers, lots of people settle for hating Castiel. It's a thing.)