Since peertube isn't backed by native torrents (only webtorrents which aren't used by most torrenters), it means that individual servers are bearing an immense amount of hosting costs: hard drive space on VPS's, network bandwidth, encoding, etc.
This is a completely unsustainable model if you look at how much these things cost the people running them. 100GB alone of space on a VPS can cost more than $40 / month. and that's just a handful of videos.
Torrents have already solved this problem years ago, by distributing these costs among hundreds of seeders on their own personal computers. All that's needed is for people to learn how to seed their own videos, and post magnet links around.