I commonly browse all by new, and I block users who crosspost any given article to more than one other community. To me it’s almost always a sign that they actually don’t care about the topic or contents, but instead their own post count and user recognition.
Given that federation naturally leads to fragmented communities it’s expected that there will be some portion of users who subscribe to only one instance of a community and so would benefit from cross-posts. I don’t think it’s necessarily conceited on the poster’s part to cross-post content that they think would be of interest to multiple versions of the same community on different lemmy instances.
Likewise it’s also natural that another portion of users will subscribe to every version of a community across all instances so that they don’t miss anything. In that case lemmy-ui needs to be able to consolidate duplicate posts across instances, and cross-posts are the natural linking mechanism for doing that. Cross-posting actually helps (or could help) lemmy to build feeds that don’t contain a bunch of duplicate articles - something which I see a lot of. I’m not sure if it’s a feature of lemmy-ui already, but it certainly could be.
Unpopular opinion confirmed. Unless you’re talking about cross-posting to multiple unrelated communities, in which case I agree.