Note: this post is in progress.
The comments are getting a refresh in the Feast Plugin.
Comments can help bloggers rank for keywords not found in their actual content.
Comments contribute to main content. Visitors reading your article will naturally have questions about things that aren't covered in your post - these questions and keywords should be added to your content, making the recipe more useful over time.
Comments encourage visitors to come back when they receive a reply, increasing pageviews.
Facebook is stupid. Comments and engagement you get on Facebook is going to disappear when Facebook changes some setting or algorithm for fresh content. Comments on your blog live there forever, gradually increasing the relevance of your post to visitors and search engines.
Rather than set the styling hardcoded in CSS, we'll add these settings to the customizer so that they can be customized.
Loading only on single (posts, pages) because comments aren't found on the homepage or category pages.
Jetpack and Disqus
More critically, you're relying on an external provider for basic functionality. Much like Facebook, these external comment systems can disappear or change with a moment's notice.
KISS - keep it simple, stupid. Use the core WordPress commenting system.