When I look at Mastodon posts, I see a decent amount of replies and boosts for popular posts, but not very many stars (see example image). I assumed a star is the same as a like, but I feel not a lot of people star a post, whereas I did see a lot of hearts/likes on Twitter posts. Are they not equivalent?
I've been on Mastodon since 2016 and never really got into Twitter. I just don't understand why the "algorithm" matters. Who cares if people who don't follow you see your post? I want my followers to see my posts, and then favorites allow me to know that my followers liked what I posted. It's a nice dopamine boost and helps me feel closer to my community.
A lot of posts I make unboostable as well (followers only). "Promotion" doesn't really factor much into my use of Mastodon so much as being "social".
As said above, likes are virtually useless. They're more like "noticeable bookmarks". Mastodon etiquette is to boost rather than like, if you enjoy a toot, and that's also how it was when the Twitter timeline was chronological and didn't include likes, a very long time ago.
Favorites (likes, stars, whatever) don't Federated, so the only favorites that your instance shows are the ones it knows about, being the favorites that are local.
Favourites absolutey federated. They just follow the same federation rules as everything else: They federated from actor to follower. So, if no one locally is following a remote user that favourites a remote post, that favourite doesn't get sent to your local server.
O, I see. That makes sense. A bit of a bummer, because having a total number of likes would be more informative (imho) than only seeing the number of your own server.
On Masotdon, likes don't do anything to extend the reach of a post or make it popular in an algorithm like Twitter. It's literally just a regular like/favorite button, so use it if you want to like/favorite a post.