Blogging, in many ways, helps benefit people by allowing others to connect, share, and converse with each other. Tumblr is a great example for this. There are downsides to blogging as well that are not so great but come with the packaged deal, so to speak, anyways.
Sometimes blogs can get very popular very fast and it becomes difficult to truly enjoy what it means to blog when it comes to meeting and conversing with so many people. There just isn't enough time to reply to all of them, let alone remember what it was you were talking about with one of your followers. There just isn't that same connection.
Or it could be the opposite scenario. Someone sets up a blog to talk and chat with others and no one even bothers to view the page. They talk and talk all they want but there isn't even anyone to talk with. The people are busy somewhere else doing whatever it is other people do in their spare time or on other blogs conversing. The sharing becomes pointless and all the time and effort to set up a blog and write what you wanted to talk about just didn't work.
Other than that, issues may arise of people wanting to talk with you so it requires you to be an active blogger. It makes you have to check the blog daily and write something down to pretty much say, "Yeah, I'm still here." It can become frustrating if you just want to back away for a little bit but the blog may not be the same as when you left it when you come back. It just works out this way that some people may be unhappy with how you're running your own blog, and then arguments start. It's not very pretty to have a flame war in your own blog and some hurtful things can be said on both sides. It leaves you stressed when a blog shouldn't be stressful. Lots of things could happen but it is the internet.

"Expect the worst, hope for the best." - Angela Carter