I’m sure there are some good reasons, but I don’t know what those reasons are.
I’ve noticed that sometimes the instance of the community doesn’t match the instance of the user who posted there, and I was wondering why they chose to post to that community instead of an equivalent one on the instance they joined. Are there pros and cons to doing this?
Well, on Reddit people often do create new communities for the same topic because they don’t like the rules/culture/mods of the original one. So would you say that’s the same reason for choosing a different community on the Fediverse?
Yes, but they can’t make use of the name on Reddit. So if you didn’t like how r/movies was made, the odds are there’s no intuitive name for a subreddit to take left to try and compete with them.
Not that you even can effectively compete with them because subreddit promotion on reddit is total garbage.
That happens sometimes: https://feddit.org/post/7025680/4263481
Certainly to an extent. Though the fediverse model is much more elegant and clear. Plus it offers massive benefits to organizations. Seeking to have communities and comms that they can truly call their own. Maintaining as they see fit. The KDE and blender groups for instance have their own servers and their own communities on them. That they can manage and focus on just their projects. No missing on the servers with toxic political communities like leninists or fascists. Just their projects and only their projects or things related to it.