Any post and community could be accessed through a theoretically limitless amount of instances, which also means a theoretically limitless amount of URLs.
Will this hinder Lemmy from ever coming into the mainstream? If I type any topic in Google, I will get a reddit thread that deals with that. Can something like that ever happen for Lemmy?
Currently it appears that a non-logged-in user (try an incognito window!) will only see posts on a particular server’s local communities. So a search engine bot crawling multiple Lemmy servers will only see duplicates if they’ve been explicitly crossposted.
No, you can definitely browse “all” while logged out. It just defaults to local.
Yes I’m sure that it won’t take too long for search engines to cotton on and start indexing Fediverse stuff - after all it’s going to be getting linked from other sites, which will cause the spider to head to the source URL and start having a gander.