Also, since 4.0 you can follow hashtags. Currently a restriction on this is that you only see posts that made it to your instance because someone else on your instance is following the author. So it works better if you are on an instance with many users or users with similar interests to yours. It works very well for my use cases, most of the content I see is through hashtag follows.
If I want my followers to see something, I have to consciously make a post that says "hey check out this thing". It's great! I open Mastodon, look at what the people I'm following are saying or pointing at, and then I close it and get on with doing something else instead of spending half an hour being distracted by Shit Twitter Thinks I Might Like.
My understanding is that the Mastodon devs are trying to separate "increase the distribution of a post" from "give positive feedback to the post author".
I do like that there's no reply component to boosts though. You boost it up or not. No sniping.