Google "History Blog" or anything similar and links to "Top 100 History Blogs" or something similar will show high up in the search rankings. Investigate a top blog in such a listing and find that their latest post was done months and years ago. Not always but too often. Is it too much to ask that one of the criteria for judging a blog to be "top" is that it is still active?
Two suggestions to improve "top history blog" listings: (1) disclose selection criteria and (2) set an "as of" date, such as "Top History Blogs of 2015".
These top lists reflect badly on history blogging in general as well as history groups in social media. Contrary to the impression given by those top sites, there are many fine history blogs going on.