PieFed dev Rimu answered at https://piefed.social/comment/12376368:

The posts in that community will be deleted after that many days. For remote communities this only affects the local copy of each post and the post will still exist on the source instance and other instances (unless they too delete their copies). For local communities the deletion federates so the post is removed everywhere.

PieFed is intended to run for decades and storage costs money so admins can set how long they want to retain content for, on a per-community basis. It’s up to them to decide what is worth keeping forever and what should be trimmed.

AFAIK piefed.social has ‘forever’ for the retention of all local communities and only trims remote communities. In some communities piefed.social only keeps posts for very short periods, like 28 days, because it’s the kind of content people look at once and has no lasting value beyond that.

The one thing Reddit has is over a decade of archived posts that answer even the stupidest question.

Exactly, which is what I want to see with the Fediverse. Could be a PieFed thing yes.

It really depends on the community. If the community is mostly discussion based help, it's a bad thing to delete it.

If it's a community of spongebob memes, it's less of an issue to delete old posts.

No, PieFed posts have a 'canonical' meta tag which sends search engines to the original post. The local copy of a remote post is never indexed by Google anyway.

https://ahrefs.com/blog/canonical-tags/

Deletion of unnecessary data is a cost-saving measure which makes it much less likely that piefed.social will need to shut down forever. Lots of fedi software doesn't do this and it has bad outcomes. Check this out:

mastodon.cloud has 1,300 active users:

Their running costs are $800 per month and now they're shutting down.

I don't know all the reasons why they're closing down but clearly that is an insane amount of money for a service supporting that many users.

PieFed.social has 1600 users and costs whatever the electricity for a 10 year old computer is. $5 per month? On a Hetzner VPS it was about $50 per month.

This isn't big tech where more data means more share price or more AI training data or deeper ad-targeting user profiles. This is smol tech where more data means more problems. If we want to preserve any content we need to delete some content.

But I do think we’re in a data hoarding mentality and wish to preserve everything. I think it is important to let things go.

In general I'd agree, but I'd like to see a Web where search engines show more answers on the Fediverse/Lemmy instead of Reddit. If the default is removal after 365 days, this won't happen.

reddit posts were read-only if they were older than a few months until pretty recently

it will certainly delete useful content too.