I a always amused when someone jumps on an idea of mine, or one of my projects, proceed to tell me how stupid I am, then point to some similar technology or approach had previously failed. First I always take it as a lesson, and make sure I fully understand what they are referencing, and spend some time understanding what happened.
There are plenty of previous technology implementations out there, successful and failed that we should learn from, and I would never miss a opportunity to better understand history, regardless of how I'm introduced to the concept.
Even with the lessons that come with these outreach efforts, I can't help but think how absurd this type of trollish behavior is, and that because something has failed, I should not be trying it again? Most often these efforts are shallow, with people not even reading my full post or understanding what I'm trying to do, and they quickly associate it to their world and tell me how stupid I am to try something that has already failed.
The lack of critical analysis is clear, because if you really think about things operate in real life, at least for me, when I fail, I work to learn as quickly as I can, and keep trying until I succeed. I would never see a failure as a stopping point, I see failure as opportunities to learn from, regroup and try again.
Although I think that many of these folks who feel the need to reach out, and remind you of previous failures, probably do not learn from failures in their lives, they just recoil from each failure, pull back and never do those things again. This stance make for a rich environment to shoot down other people’s ideas, and because of insecurities, they always feel compelled to try and tear you down.
Maybe next time you want to tell someone their idea is bad, because it failed, you might want to say, “have you taken a look at the previous failures of X, to see what you can learn?” Rather than just shooting someone down.