I think the concept of the Fediverse is still really alien to people, even the people who are using it. Everyone is still so used to their centralized platforms, so they still think of the Fediverse in terms of platforms rather than as a whole.
You still hear people say “Mastodon” to mean the microblogging corner of the Fediverse even if they’re not actually on Mastodon, and now people say “Lemmy” to mean the link aggregation corner of the Fediverse even if not everyone is actually on Lemmy.