Complicated question. Dismissive comments about new things bother me partly because there's an asymmetry that seems unfair. It's so risky to create something new, and so easy to dismiss it. At their worst, the people making such comments are like schoolyard bullies picking on someone who tries to do something different.
This particular case is very mild-- more confused than dismissive really. It just struck me as funny to see it get upvoted so much.
The upvoting often bothers me more than the comments. There are often individual stupid and/or mean comments languishing down on HN threads. They seem pretty harmless as long as no one upvotes them, like cranks shouting on streetcorners. But when large numbers of people upvote such comments, you start to have a mob. And to see a mob persecuting someone who tries to do something new is much worse than seeing an individual bully do it.
There are still a lot of things to be figured out about forums. I predict the world will evolve techniques and customs to protect against this sort of thing, and look back on our era with pity and horror because we didn't have them. But it will probably take a while. I know how hard the problem is, because this is the aspect of HN I most want to improve and spend most time thinking about, and I rarely make progress.