Ah, but you might be surprised at the deal we negotiated. It ended up very different from the boilerplate. That's where an agent comes in handy.
Mr. Hutson, you've mentioned this several times in various discussions, that an agent comes in handy or is helpful with contract negotiations even with small or no-agent-required or micropresses.
The problem is that's not really the point being brought up when we mention sales records/lack of sales to agent-only imprints. No one disputes that an agent who knows what s/he is doing can be helpful in contract negotiations even with a house where agents are not required to submit. The concern, and the reason why this point comes up in threads, is that--not discounting the other benefits agents provide--
writers seek agents because agents have connections with publishers that writers cannot themselves reach. (There's a whole subset of points there, too, like how the reason they have those connections with editors is because the agent has a reputation for submitting solid commercial work, etc. etc.) But in the main, writers seek agents because agents can get them past the door at large publishers, and the reason those agents can do that is because the agents know those editors, have worked with/sold to them in the past (or worked with an agent who does/did), are known to those editors as representing commercial work, and have reputations among industry professionals for being themselves professional and skilled.
If an agent has no sales to agent-only publishers or imprints, it's a sign that the agent in question does NOT have those connections, does NOT have the ability to select work publishable by the Big 5, does NOT have a positive reputation or any real standing among industry professionals, and therefore does NOT actually provide one of the major benefits an agent is supposed to provide an author.
Editors ignore submissions from agents they don't know just the same way they ignore submissions from unagented writers. Sure, they *might* give it a slightly closer look because it's from an agency, but it's not remotely the same as being contacted by an agent they know who says, "I have something for you." What's worse is that if those submissions are substandard (which they often are), then the next time that editor sees that agency's name, chances are they'll skip it altogether; they already know that agent isn't someone they take too seriously.
What kind of royalty rate an agent managed to negotiate with a publisher so small that sales are likely to be <250 copies is nice, but not really that meaningful. A good publishing lawyer can do the same a'la carte, and many do. An agent is supposed to have the industry knowledge and connections to get his or her clients' work right under the noses of editors at agent-only houses, to offer sound and knowledgeable advice, and to help guide the writer's career.
All the "better contract terms" in the world aren't really going to make much difference if the agent isn't capable of performing the chief job of an agent: to submit their clients to editors who only read agented submissions. An agent without those connections hasn't spent enough time in the world of commercial/trade publishing to be familiar with how it works, and is thus likely unable to perform another chief job of an agent, which is to provide sound and knowledgeable advice.
That's why "hasn't sold to any agent-only imprints" is an issue. It's not about contract terms. It's about connections.