[brokenmachine]

>I'm not really familiar with IPFS, what does it mean that unpopular comments disappear? Is it like seeding the only torrent (comments) that you like?

Uploading to IPFS is like creating a torrent for any file you share. Someone always needs to be seeding that file for it to remain accessible to people.

So what OP meant by unpopular comments disappear is that nobody would be seeding them.