Blogs typically have their own section of comments on your pages. However, for some reason, it is common for some blogs to disable its commenting section due to some strategic reasons. It is always good practice to have an animated section commenting to start a conversation between users. After all what is the purpose of having a blog. This may be more, especially if it is a third-party commenting platform. They will provide a good measure of connection to other social sites like Twitter, Facebook, just to name a few. Possibly can attract more readers and build a community in itself.
There are dozens of known third party commenting platforms that you can choose for your blog. Here are the five platforms that comment you might want to try to your website / blog. Everyone has their specialty and features.