There's also the fear that putting words in public opens me to criticism, if someone can think of a better way of doing things, if my mental (or worse, technical!) model is wrong. Someone may take it too far and it leaks onto my personal life. In reality I see far worse practices than mine at work every day, so I hope if someone stumbles onto my blog that they get value out of whatever they read. It's also published with hugo on GitHub pages, absolutely no ads, and I'm not selling anything - for me, the blog really is about giving back.
Lastly, time. Today I knocked out a blog post on a light topic in about an hour. No revisions, just finished writing it and hit publish. I thought of the topic over the weekend and today was just put a few short examples and write about them. I'm not positive that I was detailed enough, or my explanations are good enough, etc. So time is another big factor, unless you're willing to risk publishing mistakes due to lack of polish