For most people FOSS is not a feature at all. I'd go out of my way to use something if it's FOSS, even if it donsn't solve all my problems, instead of using a more featureful app that is proprietary. Because proprietary software is a trap.
The FOSS software that is popular is not used by normies because it's FOSS, but because it's really good: VLC and Firefox come to mind. For people who have a need for it, Blender is another example of extremely high quality software.
Peertube, by it's decentralized nature, is not going to be as fast as Google's servers for YouTube, so most people would actively avoid it. The irony is that if more people used Peertube, it would be faster.