I think generally speaking, you can make the distinction between something like lemmy/reddit and something like mastodon/twitter as putting interest/community first or putting the individual first.
Lemmy/Reddit is great if you want to follow a specific topic and don’t necessarily care about what the individual users think. I don’t know about you, but I barely ever read or acknowledge someone’s username on those platforms.
Mastodon/Twitter is great if you want to follow specific people for their opinions. Like seeing what certain politicians or analysts have to say about developments in Ukraine. Things that might be interesting but not quite newsworthy, or putting news into a different context.
For any given interest you have, there are probably some voices who you care about hearing from more than others, be it just because you know them personally or because they are experts in their respective fields. Microblogging platforms are built to support that individual-first approach.