It came late (but at the perfect time) -- it lowered the barrier to entry -- it changed the default licensing -- it leveraged existing systems (github).
In short, it didn't do any amazing -- but by simply combining the right tech at the right time, the result is something IMHO much better than pip or gem or X.
You might be surprised. "Perl Artistic License" is not GPL. Python is largely a slightly tweaked BSD, I think, certainly it's not GPL. Both tend to release packages under the same license as the implementation. And so on.
This strikes me as another instance of the Node community conveniently rewriting history so they can tell each other how revolutionary they are, instead of looking around at what really has already been done. I don't know of any other community so prone to that, consistently and persistently, even after being corrected.
Also, the MIT license was essentially universal for Ruby projects, popular in other ecosystems, and very widespread on GitHub before node's existence and subsequent growth.
In short, it didn't do any amazing -- but by simply combining the right tech at the right time, the result is something IMHO much better than pip or gem or X.