microblogging is something used on a much more personal level while i think forum style social media is mostly for looking for answers and posting things you do, but microblogging social media sites are for that too. also, this is not meant to be offensive, but i think that since mastodon has been in the works for like a long time, it looks more polished than modern websites, so that can be an advantage it has
My biggest problem with microblogging sites is that I have never been able to get a good, interesting content feed out of them without also getting lots of noise. Following hashtags usually gives me a mountain of retweets (or whatever) and trying to follow groups of related people/subject matter experts gives me lots of irrelevant content. Community-style social media forces people to more strictly categorize their content, I think.