Are we sure the author is not showing some unconscious bias by looking in others for traits he has (public creativity)?
There is no particular reason why public creativity is linked to good engineers. It's one way to show good engineering, sure. But far from the only way. I could see some other hiring managers arguing the opposite: if you have time to write lightweight tech posts on your blogs, maybe you are not a great engineer who will solve my company's most difficult problems.
That being said, especially for new grads, I strongly recommend showing something, anything beyond "I graduated from this university and here are the classes I took".