No one like to be the bearer of bad news, this includes buyers. I know some sellers may find that hard to believe, but even when another product aligns better with their objectives, human nature kicks in, and delivering the news that you lost, is not pleasant for most buyers. So what do they do, they either pass the buck to someone else, like procurement, or avoid your call for weeks, hoping you’ll eventually get the hint; or any number of ways to avoid an unpleasant task.
Goes without saying, they don’t have the same issues saying yes, and mostly because they have been conditioned to understand that sellers look for YES, and try to avoid NO. But once you get beyond the cultural hang ups, NO is probably the best response one can get, as long as they are ready for it, and prepared to deal with it.