Earlier quoted context omitted.
> There are ideas that are not allowed here. It would be more accurate to say that some ideas require more work here. The reasons why are open to debate.
Here's an HN bubble aspect. You can't use any title you want, for example, they will regularly edit the title and thus effectively change the general meaning of the submission as read by most folks who just skim titles. Which has the knock on effect of making the post less (or more) desirable for users to read/upvote. For example titles starting with "How I ..." are auto stripped to "I ..." there are quite a few othe…
In which case I urge you to, when you see an example where you think the policy has indeed had a negative effect (which I'd also suggest isn't quite as basic as "did it lower the expected number of upvotes" but also "and not because it removed clickbait from the title"), either comment mentioning dang's name and saying why you feel that, or send him an email to the same effect (hn@ycombinator.com)
Not only have I often seen him engage in discussion and be open to changes for a submission when people felt a title shouldn't exactly fit HN's usual rules, but I'd also expect him to be open to changing the rules themselves if your feedback leads to his agreeing that there's a trend of submissions having the meaning of their title unfairly changed due to the generally good rules.
All that said, it's not really an example of a "HN bubble", nor of an "idea" that isn't allowed on HN.