Kind of a combination maybe? Since Mastodon lets you find new people with similar interests by browsing what’s on your local timeline or hashtags of interest, and you can still follow people of interest without any chatting. I don’t know much about chat apps but don’t you have to already know the people beforehand, or come across them via a mutual acquaintance or invite to a chat room?

Of course, Mastodon can be and is used for broadcast/consume interactions, but not as much, since most broadcasters want a huge audience with little interaction, which means a big platform, while the ones on Mastodon are probably looking for a bit more interactive experience with a smaller audience.