Nobody needs to be seeding if only one download is active. You could self host an image at home on a Raspberry Pi and provide an image in a minute.

Nobody's CI should be depending on an external download of that size.

We are talking about replacing the docker hub and the like, what people "should" be doing and what happens in the real world are substantially different. If this hypothetical replacement can't serve basic existing use cases it is dead at the starting line.

> enough people seeding

the .torrent file format, and clients, include explicit support for HTTP mirrors serving the same files that's distributed via P2P.

Archive.org does this with theirs. If there are no seeds (super common with their torrents—IDK, maybe a few popular files of theirs do have lots of seeds and that saves them a lot of bandwidth, but sometimes I wonder why they bother) then it'll basically do the same thing as downloading from their website. I've seen it called a "web seed". Only place I've seen use it, but evidently the functionality is there.

I'm pretty much convinced the people at Docker have explicitly made their "registry" not be just downloadable static files purely to enable the rent-seeking behavior we are seeing here...

Cache images locally. Docker has enough provisions for image mirrors and caches.

Downloading tens or hundreds of megabytes of exactly the same image, on every CI run, on someone else's expense, is expectedly unsustainable.