Disclaimer: I wrote this article and made this website.
There was some talk of this issue in the recent fediverse inefficiencies thread. I’m hopeful that in the future we’ll have a decentralized solution for file hosting but for now I deeply believe that users should pay for their own file hosting.
Ok, so Lemmy doesn’t cause the same amount of duplication, but I’d still argue that dedupe is valuable: it saves on hosting costs (your costs, in this case) and users will get a small advantage in having slightly higher cache hits.
For sure, I’ll add it to the list. :)