GitHub is another example of a company that caters to the open source community while still having a business plan.

Right now npm is at the core of every project using node.js, and businesses have more complex needs than open source projects. One such need would be having a private registry. You don't want to have your production build chain depending on packages that could be replaced by the author at any point in time. The current wisdom if you want protection from that is to run your own npm server, but why do that when you can just have the guys that do this exclusively do it for you?

This makes sense because there are business needs that don't overlap much with the open source world that they can sell, the same way GitHub does. GitHub was successful because they got the programming world using them for their open source projects, and after dominating over that market, those programmers took the service and recommended it to their employers, because that was the tool everyone was using.

Npm falls in the same business area, where the programming community is already using them, and businesses have other needs from them, that they currently cannot provide.

It would be nice for npm to put up a monetization blog post to clear up the confusion.