It seems like something I hear perennially, but that may just be as someone who graduated from an extremely liberal high school in the past few years and went on to spend time with book-minded liberals and then on the West Coast.
There are gay teens in YA literature. In fact, there's a whole genre of coming-out literature.
Which is why we need more gay teens in mainstream YA. Coming-out fiction is generally awful and formulaic - like Horatio Alger's rags-to-riches stories that proliferated like rabbits in the 1860s. You only need to read one to have the whole genre down. You only need to read two to be a little bored of it. You only need to read three to sincerely believe that gay teens need to be better represented in other genres so that gay teens don't need to read this awful shit to find people whose orientation they can relate to, because at least minor romantic subplot interests most teens.
Coming-out literature is of limited use: most people only need to come out fewer than a handful of times. Fiction in which gay teens are out, and are doing interesting stuff to which being gay is fairly tangential and being awesome is primary? That's always going to be a interesting.