DoomSayers are those people who explain to you why what you are doing successfully can't possibly work, usually by invoking demons from hell.
Sometimes they are right. Always they are a good hint that you aren't expressing yourself very well.
See also NuclearWinterAndWarmHeatDeathOfTheUniverse
BertrandMeyer says that reaction to a new methodology goes through 3 stages:
(The order may vary). I think there's a related pattern involving industry hype followed by cynicism and DoomSaying. -- DaveHarris