Isn't Mastodon the Twitter alternative? I never understood the appeal of Twitter so I don't get the need for an alternative. Anytime I hear mastodon mentioned I'm confused by what the heck people could possibly be using it for
Exactly. One uses an algorithm to suggest stuff you like based on other things you like. Say, webcomics. If you like a creator and what they post, you can follow them. Twitter will then suggest users who post similar content so you can follow them too. On Reddit/Lemmy, you'd need to find an appropriate subreddit/community. You can follow people once you stumble across them, but it's not quite as easy to find them. Reddit will also not suggest posts and content based on your interest but instead will show you what's highest voted by others or currently trending in general.