If different data always gets a different reference, it's easy to know if you have enough backups of it. If the same name gets you a pile of snapshots taken under different conditions, it's hard to be sure which of those are the thing that we'd want to back up for that particular name.
https://github.com/internetarchive/dweb-archive/blob/master/...
(this doc is 5-6 years old though, and I'm not sure what may have changed since then)
In my own (toy-scale) IPFS experiments a couple years ago it has been rather usable, but also the software has been utterly insane for operators and users, and if I were IA I would only consider it if I budgeted for a from-scratch rewrite (of the stuff in use). Nearly uncontrollable and unintrospectable and high resource use for no apparent reason.
What's the point of using IPFS then? Others can still spread the file elsewhere and verify it's the correct one, by using the exact same ID of the file, although on two different networks. The beauty of content-addressing I guess.
Especially if it's about having an Internet Archive backup.