I don't ordinarily read the Hacker News site but Mastodon is trending on it again so I thought I'd read the comments and see if anything can be learned from them. The TL;DR is that there isn't really anything new here. It's the same misunderstandings as existed a year ago.

The top comment, that is, the one with the most votes, provides a good indication of the most common misconceptions.

you want me to get excited about Mastodon? Show me something exciting I can do with it that I can't do with twitter, instagram, or Snapchat

This assumes that there is some set of technical features which are better. There are a few, but to focus on those misses the point. The main point of the fediverse is that it's not centralized. It's has federated governance rather than being a dictatorship by some deluded CEO. Fediverse systems are also Free Software, so you have the advantages of the freedom which that provides. I can't fork Snapchat and make a customized version of it.

Alternatively, is there some new and novel porn that Mastodon will allow me to access?

I don't know of any porn instances as such, but in principle there's nothing to prevent that happening.

Or is there a new generation of FIFA stars on Mastodon? Or new generation of NBA stars?

This assumes that celebrities are what social life should be about, and there is no point in joining a system which doesn't have them. Not having celebrities is really a feature not a bug. Celebrities only provide the illusion of community. They're not actually a substitute for developing real relationships, and are a distraction from that. Celebrity culture is broadcast culture. It's not about participation or reciprocity.

There's nothing to stop celebrities from creating their own fediverse accounts. In the past some did that. But they always quickly leave once they realize that they're not going to get millions of adoring fans, and are not immune from criticism or from being kicked off if they abuse their welcome. This is in contrast to Twitter, where celebrities can break the rules but receive special treatment because of their status.

I mean, it might work? But I think Las Vegas hit on a much better method...

The fediverse isn't about stars, or creating stars. Nor should it be. The fediverse is more about friends.