I feel that this sort of criticism is less about the actual plausibility of ideas, and more about the intense competition for resources amongst startups right n

I feel that this sort of criticism is less about the actual plausibility of ideas, and more about the intense competition for resources amongst startups right now. People are more positive about new ideas when there aren't five hundred copycats competing for the same limited pool of attention, office space and employees with tiny variations on the same basic themes. When there's one "stupid idea" making a run at the barricades, it's easy to be supportive. But when every idea immediately clones three other "fast follower" ideas, people get cynical pretty quickly.