If it’s advertised to work in that way, and I as a user know that, then I don’t consider it a bug. Like a text-only web browser, for example. I know what to expect because of what it’s obviously designed to do and not do. But if a nostr client is supposed to be a general purpose social networking app, and the only way to have a consistent/reliable experience is to only communicate with people who also use that app, then it doesn’t need to be nostr. Either that, or people need to stop touting nostr as place where you can login anywhere and see your content and social connections. Right now there is either a mismatch in development, or in messaging.