I was wondering if the editor meant being so wrapped up in your own words the story doesn't get told and the audience is left wondering what the hell happened. Even if you were trying to tell a story you knew the audience would love.
And a large portion of the job of editor is communications and ego soothing. Every time an editor gives advice, they need to explain their reasoning rather than giving out knee-jerk pat sayings that help no one. If an author doesn't understand your advice, it's as if you offered no advice at all. If they can't explain themselves in an understandable way, then you simply can't work together as a team. The other half of that, is that authors typically get bent out of shape over 'their' words, so editors need to put their egos aside and be able to explain why certain changes are necessary, even if the author initially rejects their arguments.
If an editor tells me something is wrong, I'll often say "No, that doesn't fit the story," but then I'll invite them to argue with me. Often, they'll come back and say "No, it should be this way because of X and Y". If I, as the author, then explain, "I understand that, but this is a personal choice for MY writing, then the editor needs to understand the author is intentionally breaking the rules for effect, rather than simply not understanding what they did wrong. That's when you back off as an editor. Mistakes made in ignorance are bad, but writing "just like everyone else" can be equally as bad. Again, authors typically know their own audiences better than editors who've never read the author's work before.
That said, the claim that authors "love the sound of their own voice" often implies that they write 'flowery prose' which doesn't add much to the plot. Even so, many readers prefer that. I'll often pick up books in a library, read random sentences on random pages, and if the language can captivate me, I'll purchase the book regardless of the content, knowing the writing alone will captivate me. So again, it's knowing your actual audience vs. the editor's desired audience. However, if an editors calls you on your use of language, it's generally time to step back and ask whether you're over doing it. However, if you strongly believe you're using it correctly, then you've got to be willing to stand your ground, to the point of firing your editor if necessary.
Unfortunately, if you fire an assigned editor, you'll end up paying for both that editors time and the time for an entirely new editor to start from scratch, so often we compromise with bad choices because we don't anticipate humongous sales. :(