Any idea why this needs such wide permissions like managing my apps and extensions and reading my history?

Wow! Thank you very much I never thought of looking for an extension. For a very short time I found that feature in my search results directly. Then it just went away.

Yeah, Google did that for a short time. I used to use it to filter out content farms. They've gotten better at filtering content farms since then, and dropped the feature - probably because it was too expensive resource-wise to personalize results like that.

Not sure if it's very functional. I blocked W3Schools + Wildcards (because I'd rather read MDN) and after a few months of working their results continued appearing at the top of my page.

There are a few blog posts around the net where some users have tried similar and found that W3 schools was also serving up content from another place that had not been blocked.