9 out of 10 times, blogs are extremely stale content from 5+ years back. A lot of people start blogging at the beginning of their careers and then just stop. This creates a weird frozen-in-time effect where what's shown on their blog doesn't match their current skillset at all.
I've read enough personal blogs that I know to look for timestamps and put it in context. If I see a "Ruby on Rails TODO app MVP" blog post or Github repo dated 8 years ago, I'm not going to use that for consideration in hiring them.
However, not every resume reader is going to be that considerate. If your blog isn't up to date, you may want to omit it from applications to avoid giving someone the wrong impression that you're still a beginner.