They might be here to cause annoyance and not get sats tho(?)

That's the thing though, there's no proof of work required to post on the nostr. That's probably the answer, ultimately, as if we require a certain amount of proof of work, because then you can't post indiscriminately. Are you willing to let your cell phone battery get hit by some computation to post your note? Probably. But if you want to post multiple times a second so that you can spam people, it's different.