When agents reply, "It's good, just not for me," isn't that admitting to being gatekeepers to traditional publishing?And here are my thoughts:
There are a few reasons why. Here's one:
There's a subjective element to books. I might read a book about wereferrets and think "this has a great voice but I don't like ferrets" and another agent might read and love and think "this is the best thing I've ever read."
This isn't gatekeeping because not all agents have the same taste. I've read books before that I probably wouldn't have requested at the query stage. But those books still found an agent and still got published.
Plus, editors do the same thing to us. Let's say I did sign the wereferrets book. Not every editor would want it no matter how good it was. Even huge bestsellers or books that go to auction still get some passes. If it's well written with a good voice, I'm sure they see that, but they also just might not fall in love with the wereferrets.
And it's not just them either. Editors also have to "sell" the books they want to take on to their team--publisher, sales, marketing, etc. Sales might say--sure this is good, but we can't sell wereferrets to the major accounts so no.
And they say that because they're interacting with bookstores and the accounts (major retailers) and those buyers are saying "no we don't want any shapeshifters, we're not going to order any copies of books like that." Or maybe sales remembers how last year they tried to say a book with werebadgers and that book only sold 200 copies because none of the accounts ordered it to carry in store. Therefore they don't think wereferrets will be much different.
And the retailers, they're making that decision based on what they think their consumers want. Which they're determining based on the what the consumers are actually buying--or not buying. If they order 100 copies of a book about werebadgers and only sell two copies, they're not going to want any copies of a book about wereferrets.
So really it's the consumers that are driving the stores, and the publishers, and the agents. That's not to say that there aren't readers out there hungry for a story about wereferrets--it just means they're not buying books like that at traditional retailers. Maybe they're only buying ebooks. Or maybe they're reading fanfiction and pirating ebooks. Maybe they're only buying books from shapeshifting fandom conventions. I don't know (this example is getting out of control, but I hope you see what I'm saying).
Now here's another reason:
"This is good, but it's not for me" might not be the truth. There might be a harder truth, like "This is good, but it's not good enough."
I really like clothes. I get one of those monthly boxes that sends you a few clothing pieces and an accessory. Last month, it included a pair of earrings that were gorgeous and I really liked them. But they were $50 for just a little pair of earrings that weren't anything super special. So I liked them, a lot, but I didn't $50 like them.
Sometimes manuscripts are the same way. I've said I really like fantasy. Let's say I request a YA fantasy. I might read to the end, I might think, "that was a good read" but I do a lot more for my clients than just read their books once. There's the reading and the editing, but there are meetings and phone calls and strategizing and a lot of hours that go into that client's career and their books.
And there's only so many hours in a day. I can only take on so many clients. So I might read that YA fantasy manuscript and think, this is good, but it's not good enough for me. Maybe it's the characters or the pacing or the writing. Or maybe it's not even anything I can put my finger on. Maybe it just doesn't stay with me after I've put it down. Whatever it is, I don't love it the way I loved Gates of Thread and Stone or Red Queen. So it's not for me--because I only have time for things I love that much.
Sometimes it's hard to articulate that to authors. Even us agents don't like to discourage people or hurt people's feelings--and there are a lot of agents, maybe someone else will see something I don't or they'll have the time.
So that's a long answer to your question. I don't think we're gatekeepers. I know it's hard to get a book traditionally published--and that it's hard to get an agent. But the internet has made it easier than it was. Keep writing. Write a great book that you're passionate about--even if the characters are wereferrets! Then write another book. And keep going. At some point, you'll get there.