I have interviewed hundreds of candidates, not just red their CVs (typically around 1 candidate a week for the past 15 years, currently 3 candidates a week on average).
What I have learned is to be very cautious when looking through CVs lest you select for candidates who can make good looking CVs.
I have met many nice and competent people who don't write blog post and who can't make nice CV. They don't make projects for show because they have enough work at... work and they don't do ten other projects because they want to focus where it really matters for them. They might have other non-technical hobbies like riding a bike or picking up girls at the bar. They may not feel the need to impose their interests and thoughts on everybody else or they might think their thoughts and experiences are not at all valuable to general public.
A person who writes blog posts, for-show github repos, who creates public image, is just one of many types of developers. If you select for this you are missing out on many excellent people.