Crossposts might be annoying, because

• essentially they are the “repost” feature of lemmy. And repeats might be low quality spam, because you have to look at the source, how often it was reposted already, etc.
• crossposts might seem like a cry for unwarranted attention, but they might be necessary in a fractured federated system like Lemmy …

Or do you not care when realizing “this is a crosspost”?