Isn't that a pretty significant difficulty for the interpretation of this number, though? Couldn't there be some package that is installed by default in, say, Ubuntu (and that Ubuntu can't boot without), so therefore millions of users are using it -- but perhaps the "downloads" seen by GitHub or SourceForge are mostly by OS packagers or by developers contributing to that package. Whereas if there is something where, for some reason, end-users customarily or commonly get it from GitHub or Sourceforge, it might look more widely used even though it is actually less used overall, potentially even by orders of magnitude.
(Like GNU coreutils, at an extreme, is probably not that popular at all for end users to download from a source control system, yet it might be running in tens or hundreds of millions of devices, which could not even boot without it.)
There will always be edge cases and scenarios we are not taking into account, please provide feedback on issue tracker and provide any suggestions so we can account these.
This ranking is very flawed if I can literally go to Best Buy and get a replacement for "critical" software.