There’s a few, but a significant one is that I’m familiar with how npm organizes information whereas package pages organize in many different ways and sometimes put marketing spin on it.

So I like finding npm in my search results so I can see release history and other package metadata.

Also, like I said, npm is more trusted than lots of different developer pages so knowing something is a package is useful and not immediately apparent from going to a project page or GitHub repo.

It’s not that it’s impossible to find this info outside of npm, it’s that it’s easier to mix npm results in.

Also, generally I want to be able to search all relevant info in the universe. Trying to keep track of what exists and is excluded, especially if excluded to prevent spammers, is a waste of my thoughts.