Most fans won't ship the best friends. For Harry Potter, Harry/Draco far, far outstrips Harry/Ron. For Teen Wolf, Derek/Stiles and Liam/Theo are so much more popular than Scott/Stiles and Liam/Mason. For Psych, Lassiter/Shawn is more prevalent than Gus/Shawn. And so on.
Also, in a lot of the long slash fic that I read, because so many canons have so many male characters, the slash couple often has male friends which are part of the story, so I do not agree, at all.
In a lot of fandoms, the opposite is true.
Also, in a lot of the long slash fic that I read, because so many canons have so many male characters, the slash couple often has male friends which are part of the story, so I do not agree, at all.