As a supporting evidence about the spam point, here is the last post on their piefed support community:

Sorry for the delay, I'm a new admin and I was only a lemmy user. Some admins have been a bit busy IRL so a few things have gotten a little behind.

I've taken a look over there and I'm now starting to keep a bit of an eye over there.

Of course, we're all volunteers, and while sometimes we're EXTREMELY quick on spotting spam, it can also be an hour (or few) if we're not around and/or it just doesn't pop up in a way we notice.

So definitely report spam you find. Personally, I wouldn't mind a PM if you'd like. I'm still learning some of the fediverse bits. I'm working on some tools to help make some of it a little easier to moderate - for example, reports on lemmy.world are decent for moderators, but it's a bit more difficult for them to be useful for admins, so it's often better to start a thread here or use one of the other methods to contact us for when an admin is needed.

So there are some very limited reports on piefed.world - I'm honestly not sure how we prefer y'all report spam to use, so I'll ask my fellow admins when they have a little time - but especially meanwhile, definitely poke me and I'll be glad to take a look.

(Can't speak on the outdated version, alas, but I'll pass that along - these threads do get sent to us, it's just a matter of when someone has time to address issues)

Please don't give up on us yet :)

Not sure when they will start caring but in the interim, you're always welcome over at piefed.zip!

They won’t for the same reason why they won’t ban .ml. The .world admins are too chickenshit to move in any direction for fear of losing content. Trust me that I know that’s and don’t ask how.