It has a character limit, it has separated instances on which you really can't subscribe (at least I couldn't a few years back), and it is realtime feed.
So who is the target audience really? Big influential public figures with millions followers? - not possible due to federation
Small thematic communities or specific professionals, not popular with masses? - very problematic due to federations first (all need to get on the same instance), then due to character count (no longform posts by professionals), and real time, so that rare good posts of people you care about are simply lost in the feed.
Even smaller groups of friends? - none of the problems above are blocking, but now the question is why Mastodon specifically, instead of a more usable and friendly chat room in any of the messengers.
It's decentralized twitter basically... There's more nuance but for now just consider it twitter for this examples sake.
So imagine everyone can host their own twitter server, each server connects to each other... Or inversely not connect to certain servers if they want.
Now instead of a single server being a catchall for everyone, you can have nuanced servers.. since you have both a local timeline and a federated "all servers" timeline as well as the timeline of people and hashtags you follow.
Let's focus on the local and federated timelines.
Let's say you're on a mastodon instance that's all about pokemon Minecraft, people on this server will probably share that same like.. so when you look at the local timeline you're seeing people only on your pokemon Minecraft server.
When you look at the federated timeline you're seeing EVERY other servers feed.
So instead of seeing mastodon as a replacement for twitter, ask yourself, what kind of community do you want to be a part of.... Then find that using the mastodon community finder, go sign up and post a introduction and you'll find new people on the local timeline.
Oh, that nice. I somehow missed that feature while playing around the app. Then I guess it can be at minimum current Twitter replacement. We'll see.
PS: personally I've abandoned Mastodon and never used twitter because the feed format is really not userfriendly. I prefer forums, like those older forums or newer like Reddit.
It has a character limit, it has separated instances on which you really can't subscribe (at least I couldn't a few years back), and it is realtime feed.
So who is the target audience really? Big influential public figures with millions followers? - not possible due to federation
Small thematic communities or specific professionals, not popular with masses? - very problematic due to federations first (all need to get on the same instance), then due to character count (no longform posts by professionals), and real time, so that rare good posts of people you care about are simply lost in the feed.
Even smaller groups of friends? - none of the problems above are blocking, but now the question is why Mastodon specifically, instead of a more usable and friendly chat room in any of the messengers.