I'm not sure what you are basing this on. I can say for certain that it's not true for me. Maybe it's only true in some negotiation contexts.
I sometimes sell stuff on the Internet. I put in a price and say this is firm. Many, many times, people contact me, and the first thing they do is try to negotiate the price down. I instantly blacklist them. I'm not here for the hassle. Either you are interested or not. So yes, if you are dealing with me, and you are truly interested, negotiating will harm your situation.
Also, I hate negotiating with a passion. I find it promotes double speak and adds uncertainty. Pick a price and stick with it, don't change the contract midway. If I can negotiate the price down, I won't really consider it a win. Instead, you will loose my trust. Why didn't you put in the true offer in the first place? It makes me feels that if I hadn't negotiated, you would have silently robbed me. I will thus assume you are still silently robbing me, as I'm not here to spend my time negotiating further down.