@daphnaharel some instances have better moderation policies. Also browsing your local or community timeline - some instances are dedicated to artists, some are mostly tech. So if I want my community/local timeline to be mostly tech I would switch to a more tech-oriented instance, for example.

@daphnaharel think every instance like a community, if you join a "thematic" instance your local feed could be pretty interesting

@daphnaharel One practical reason is server rules and moderation. I've heard the big instances like mastodon.social have a fairly hands-off approach to moderation, whereas others are more proactive. Another reason is server load - I've heard some people complain that the instance they're on is slow/overloaded. Finally, some instances have cool domains which means your mastodon handle looks cool.