I think it's better thought of as alternatives than replacements. It has an "official" badge for alternatives that have been somehow endorsed by the moderators

I think it's better thought of as alternatives than replacements. It has an "official" badge for alternatives that have been somehow endorsed by the moderators (or old moderators in the case of removals) of a subreddit. In the case of /r/3DS, the Discord is marked official and the Lemmy community is not.