If you already have a publishing contract, this is true. If you don't, you'll want to make sure your submission is as publishable as possible. Agents and acquisition editors no longer have the time to work with manuscripts that have more than superficial problems.
I've not seen any decline in the amount of time editors have to edit mss. at any of the trade or academic publishers I work with and for. Perhaps you should look at better established publishers?
If you have serious issues with writing, because you're not a native speaker of English, or you're dyslexic, etc. it might make sense for you to hire an editor for proofreading, even though you plan on subbing to trade publishers. Certainly it makes sense for those who plan to self-publish.
But if you're planning to to submit to trade publishers and you haven't any special circumstances, it's silly and possibly stupid to hire an editor. The editor won't know the preferences of the eventual publisher's editors, won't know house style, etc. and could make more work rather than less work.
Moreover, why pay someone to do the publisher's job?
Huh. And here I was thinking I was pretty polite, even though I grow tired of the anti-editor crusaders on this forum. Maybe you can tell me how to rephrase what was a legitimate question. How does someone who takes payment for editing justify doing so after asserting beta readers and one's own talent is all that is required when seeking to be published?
I didn't realize you were asking a question about my experience. It seemed more like sneering. Twice.
Bless your heart.
You're not qualified to edit. Your prose is clumsy, both here and on your site. God knows what you'd do to an innocent author's prose. The reference to "fiction authors" is enough to make someone with an ear wince, and your site copy is not helpful. Working for ad agencies as a proof reader doesn't qualify you to edit fiction; a Ph.D. in English doesn't qualify me to edit fiction, but it does qualify me to point out that you're a clumsy writer and likely to be an even worse editor.
Your own prose on your Website is over-larded with prepositional phrases. It's not promising.
I will assess the strengths and weaknesses of the major components of the manuscript and provide suggestions on how best to address problem areas.
Seriously dude; that's just ugly. If you can tolerate a sentence like that without physical pain, you're not an editor. You don't have an ear.
You're snotty to mods, you're antagonistic towards members who have earned our respect, and you're only here to hang your shingle.
I'm not willing to tolerate parasites who mangle English for money.