I don't think anyone is against the OP asking for startup ideas and then profiting from one of them. HN, in my experience, is a very capitalistic place where members find the idea of profiting with software to be quite exciting.

I interpreted it more as a warning that these discussions are not a good way to get startup ideas. Startups need domain experts to understand what the market will pay for, making connections, and so on.

Say somone in the pharmaceutical industry posts about their problems ordering medicines. It's a fine problem, but the point is that the OP is not in a good position to solve it, as he or she is likely lacking industry experience and contacts.

The ideas you come up with yourself are more likely to be the ones you do have the experience and connections to work on.

I felt his point was along the lines of "If a startup is like a marriage, then posting a question like this is kind of like trying to hookup at a bar. It might be fun, but the odds are poor that it will lead to a serious, committed endeavor."