Earlier quoted context omitted.
I think you miss he point. The usefulness of a per-user block list is not fighting outright spam. The statistical filters, etc, as applied by the search engine, work best here, as you correctly state. The point is to remove certain well-known sites with information about well-known topics, which is unhelpful for the particular user , me. That information is technically not spam, but it's on a wrong level, badly prese…
> That information is technically not spam, but it's on a wrong level, badly presented, etc. I'd count that kind of low quality site as spam, and the problem is that there's a basically an infinite supply of them. The boost feature is more interesting in that the curation is at least not a never-ending task. New high quality sites that I know about don't pop up all that often! It's still not an entirely robust featur…
That strikes me as a non-goal. As the search engine, you can't know what attributes a user is valuing when they boost, and so you can't know when it's appropriate to override that boost. "Better" is subjective, contextual, and comes in thousands of different flavors.