One thing that comes up periodically from certain corners of the author world is the idea that for every book published by one of the Big 5, that's one less book someone else will successfully sell to that publisher. Or that for every major book deal and advance given out, that means a certain number of smaller, debut authors will never get a shot because there is no money for them anymore.
It's an argument used by certain proponents of "traditional" genre fiction when discussing the push to have more diversity in the author pool.
"When you argue for diversity, you're taking food off the plates of other authors who just happen to be straight, white and male!" And then there's usually some twaddle about discrimination and quality and wahwahwah.
I'm not going to talk about that today.
Instead, let me remind folks that publishing is not a zero-sum game. Broadening the author pool also means broadening the reader pool and that means not only more books - as opposed to the same number of books only with different authors than last year - but more money. It means more folks saying "Hey! Maybe this SF and Fantasy stuff isn't so bad after all. Where can I find more books?"
Recently DC announced it was adding a line of comics they intend to be focused more on female characters and in general appeal to the femme comic buyers. Notice, they aren't replacing the existing lines, they are adding to them. More books, not less. New authors, and old ones. More readers. More money. More good.
It's not a zero-sum game. It is a "Let's make money!" game. Although it is untrue that publishers never take risks on books (because they do), the key thing to remember is that it is a business. If they are buying and publishing a certain thing it's because they are reasonably confident it will sell. If they are buying from a more diverse pool of talent, it's because they are reasonably confident that there is a market for those books and those authors and that more money means more books, and more books means fewer authors of any color/gender/orientation subsisting on Ramen for extended periods of time.
Appealing to a diverse readership by default equals trying to broaden the readership. I don't know about you, but I always prefer more readers to fewer readers.
The publishing world is not like your grandma's pie which was delicious and always left everyone fighting over the last piece because there was only so much and you, your brother and your cousins all wanted it. No, this is like a Guinness Book of World Records pie - it can always get bigger next year.
We all win.