You hit the hammer on the nail. IPFS urls point to content-addressable data. These URLs can be pinned by anyone running an IPFS node. However, what's missing is an easy way to "seed" lists of IPFS files with whatever storage you have. Ideally, there's a way for me to choose to contribute - say - 30 GB of space to a particular project, and the system will take care of pinning the most-needed files, up to that storage limit. This would be useful for any number of public archival projects.

I've seen efforts where people bring up a web page that tells you which torrents to seed, based on how many seeds are active. But this is manual work, and not too robust.