Non-profits allow projects to grow beyond hobbies. Covering costs (whether that's the expense of hosting / running the project or hiring talented people to work on it) is going to be a better incentive to keep the projects alive in the long term, meaning that people can rely on them instead of being wary that the project might become abandonware in a year.
Or has this always been a thing. But it feels like a common—and celebrated—outcome for a lot of projects.